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  • Graphene and carbon nanotubes as solid phase extraction sorbents for the speciation of chromium: A review
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    C. Herrero-Latorre, J. Barciela-García, S. García-Martín, R.M. Peña-Crecente

    In the last decades, the extensive use of chromium in industrial activities has led to the discharge of different chromium species into the biosphere. The two stable chromium forms are Cr(III) and Cr(VI), which have dramatically different properties. While the first one is essential, the second is harmful and carcinogenic, even at very low concentration. Therefore, the appropriate analysis of chromium in environmental, biological, food and other kind of samples need a reliable separation and subsequent quantification of both Cr species. The present paper provides a critical review of chromium speciation methods in which solid phase extraction was employed as sample pretreatment using graphene and carbon nanotubes (and their diverse oxidized, functionalized and magnetic derivatives) as sorbents. " WITH ″The separation and preconcentration of different Cr species (Cr(III) and Cr(VI)) prior to measurement at extremely low levels in environmental, biological and food samples have been usually carried out using solid-phase extraction. This article provides a critical review of chromium speciation methods using graphene, carbon nanotubes (and their diverse oxidized, functionalized and magnetic derivatives) as sorbents.

    更新日期:2017-11-23
  • An approach to determining nickel, vanadium and other metal concentrations in crude oil
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    I. Sugiyama, A.E. Williams-Jones

    The ability to accurately determine the metal content of crude oils is necessary for reasons ranging from the need to identify the source of the oils (Ni and V) to removing components that might inhibit catalysis during refining or impact negatively on the environment during hydrocarbon combustion. Here we show that ashing followed by chemical oxidation and acid digestion, coupled with ICP-MS analysis, provides an accurate method for determining the concentration of metals in crude oil. Nickel and vanadium concentrations were measured in certified Ni and V oil standards and in various light, intermediate and heavy crude oils after application of a single vessel ashing-chemical oxidation-acid digestion sample preparation and storing technique. Prior to the ashing, chemical oxidation and acid digestion, an aliquot of the crude oil was placed in a 10 ml Pyrex™ culture tube and capped with quartz wool. The capped culture tubes were then subjected to thermal combustion, followed by chemical oxidation and leaching. The leachates and the aqueous standards were diluted and analyzed for their Ni and V contents using inductively coupled plasma mass spectrometry (ICP-MS). The measured concentrations of Ni in oil standards, reported to contain 1, 100, and 1000 mg kg−1 Ni (±2% error), were 1.1 ± 0.01, 99.8 ± 1.46, and 1025 ± 24 mg kg−1 respectively. The corresponding concentrations of V in these standards, reported to contain 2, 100, and 1000 mg kg−1 V, were measured to be 1.93 ± 0.06, 104 ± 1.3, and 1027 ± 7.5 mg kg−1, respectively. Crude oil samples, A, B, C, D and E, that varied significantly in their composition, and ranged from light to heavy, were determined to contain 5.59 ± 0.32, 4.05 ± 0.03, 6.22 ± 0.22, 33.8 ± 0.7 and 41.6 ± 3.5 mg kg−1 Ni, respectively. Their V contents were determined to be 11.98 ± 0.1, 12.2 ± 0.1, 16.5 ± 0.4, 34.7 ± 0.4, and 104 ± 8.9 mg kg−1, respectively. The results were thus repeatable on average to 4.1% and 2.75% for Ni and V, respectively; the repeatability was worst (∼8.5%) for crude oil E, a heavy (viscous) oil with a very high asphaltene content (27.2%). This modified single vessel ashing-digestion technique (combustion, chemical oxidation, acid leaching and storing) minimizes contamination and significantly reduces the loss of ash. Our results are repeatable, comparable to, and in some cases superior to those of other methods. The method is applicable to a wide range of crude oil compositions, is very accessible and robust, easy to use, and does not require costly equipment in preparing the samples for analysis by ICP-MS.

    更新日期:2017-11-23
  • Single cell patterning for high throughput sub-cellular toxicity assay
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Junfei Xia, Yuting Qiu, Xiaojie Xun, Liyuan Ma, Jingjiao Guan, Ming Su

    Cell population based toxicity assays cannot distinguish responses of single cells and sub-cellular organelles; while single cell assays are limited by low statistical power due to small number of cells examined. This article reports a new single cell array based toxicity assay, in which cell responses at population level, single cell level and sub-cellular level can be obtained simultaneously at high throughput. The single cell array was produced by microcontact printing and selected area cell attachment, and exposed to damaging X-ray radiation, which was followed by fluorescence imaging after staining. Two image processing softwares written in Python and MATLAB were used to determine the expressions of proteins associated with cell migration and invasion, and production of reactive oxygen species (ROS), respectively. The results showed significant differences in responses at single cell level and distinctive molecular heterogeneity at sub-cellular level in a large population of cells upon exposure to radiation.

    更新日期:2017-11-23
  • Commercial glucometer as signal transducer for simple evaluation of DNA methyltransferase activity and inhibitors screening
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Ying Chen, Hongchao Yi, Yun Xiang, Ruo Yuan

    DNA methyltransferase (MTase) plays an important role in many biological processes and has been recognized as a predictive cancer biomarker far before other signs of malignancy and a therapeutic target in cancer treatment. Thus simple and sensitive determination of DNA MTase activity is urgently required. The commercially available glucometer is considered as the most successful point-of-care (POC) sensor up to date, and researchers extend its application in monitoring different types of targets rather than only glucose. Here, we developed a simple strategy for the sensitive detection of the DNA MTase (using M.SssI as an example) activity by using a glucometer as the signal transducer. A S1/S2 hybrid probe was designed including a specific recognition sequence for both DNA MTase and restriction endonuclease, and a complementary sequence for biotin-S3. Firstly, the S1/S2 hybrid probe was self-assembled on the gold electrode and methylated by M.SssI MTase to form the methylated dsDNA. Then, HpaII endonuclease specifically cleaved the residue of the unmethylated dsDNA. Subsequently, biotin-S3 hybridized with the overhang sequence of the methylated dsDNA. Finally, the biotin tag was successively combined with streptavidin (STV) and biotin-invertase. The invertase efficiently catalyzed the hydrolysis of sucrose to generate abundant glucose, which led to an amplified response of glucometer. This strategy could detect DNA MTase activity as low as 0.3 U mL−1 with good selectivity against other two cytosine MTases (HaeIII MTase and AluI MTase), and be successfully applied for screening the DNA MTase inhibitors (5-azacytidine and 5-aza-2′-deoxycytidine), implying our proposed method holds great promising application in early cancer diagnosis and therapeutics.

    更新日期:2017-11-23
  • Mirror-image aptamer kissing complex for arginine-vasopressin sensing
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Benoit Chovelon, Emmanuelle Fiore, Patrice Faure, Eric Peyrin, Corinne Ravelet

    The recently reported aptamer kissing complex (AKC) strategy has allowed for the development of a new kind of sandwich-like sensing tools. Currently AKC assays have been only applied to low molecular weight molecules and their functionality in complex matrices remains challenging. The objective of the present study broken down into two sub-aims; exploring the propensity to broaden the scope of detectable analytes and designing a more robust system for potential applications to realistic samples. An all L-configuration aptaswitch module derived from a hairpin spiegelmer specific to a larger target, i.e. the arginine-vasopressin (AVP) hormone, was elaborated. The target-induced AKC formation in presence of a specific mirror-image RNA hairpin (L-aptakiss) probe were analyzed by using fluorescence anisotropy. The mirror-image kissing complex was successfully formed when the L-AVP target bound to the engineered L-aptaswitch element. It was also established that the use of methanol as cosolvent significantly improved the assay sensitivity through the stabilization of the ternary complex. Finally, the capability of the mirror-image method to operate in 10-fold diluted, untreated human serum was illustrated. The current work revealed that the AKC concept can be expanded to a wider range of targets and converted to a L-configuration sensing platform especially suitable for bioanalysis purposes.

    更新日期:2017-11-23
  • Magnetic beads modified with an electron-transfer carbohydrate-mimetic peptide for sensing of a galactose-dependent protein
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Kazuharu Sugawara, Toshihiko Kadoya, Hideki Kuramitz

    For use in the voltammetric sensing of galactose-dependent proteins, we modified magnetic beads with a peptide that had both electroactive- and molecular recognition properties. The peptide consisted of a YXY sequence and behaved as an electron-transfer carbohydrate-mimetic peptide that would combine with proteins. With this tool, the protein could be detected via a label-free system. We synthesized several penta- and hexa-peptides with a cysteine residue on the C-terminals to examine the properties of peptides. These peptides contained amino acid residues (X) of alanine, serine, or tyrosine. The peptides were immobilized on magnetic beads via N-(8-maleimidocapryloxy) succinimide. Soybean agglutinin(SBA), the in vivo function of which has been well established in animals, was selected as a model protein. The protein was detected via the changes in electrode response due to the oxidation of tyrosine residues from the phenol group to quinone. As a result, SBA was selectively accumulated on the beads modified with YYYYC. The calibration curve of SBA was linear and ranged from 2.5 × 10−12 to 1.0 × 10−10 M. With this system, SBA was recovered in human serum at values that ranged from 98 to 103%. Furthermore, the beads with peptides were regenerated five times using a protein denaturant. Accordingly, this electrochemical system was simple and could be rapidly applied to the detection of galactose-recognition proteins.

    更新日期:2017-11-23
  • Diffusion of cytokines in live lymph node tissue using microfluidic integrated optical imaging
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    A.E. Ross, R.R. Pompano

    Communication and drug efficacy in the immune system rely heavily on diffusion of proteins such as cytokines through the tissue matrix. Available methods to analyze diffusion in tissue require microinjection or saturating the tissue in protein, which may alter local transport properties due to damage or rapid cellular responses. Here, we developed a novel, user-friendly method – Microfluidic Integrated Optical Imaging (micro-IOI) – to quantify the effective diffusion coefficient of bioactive proteins in live tissue samples ex vivo. A microfluidic platform was used to deliver picograms of fluorescently labelled cytokines to microscale regions within slices of murine lymph node, and diffusion was monitored by widefield fluorescence microscopy. Micro-IOI was validated against theory and existing methods. Free diffusion coefficients were within 8% and 24% of Stokes-Einstein predictions for dextrans and cytokines, respectively. Furthermore, diffusion coefficients for dextrans and proteins in a model matrix were within 1.5-fold of reported results from fluorescence recovery after photobleaching (FRAP). We used micro-IOI to quantify the effective diffusion of three cytokines from different structural classes and two different expression systems – tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), and interleukin-2 (IL-2), from human and mouse – through live lymph node tissue. This is the first method to directly measure cytokine transport in live tissue slices, and in the future, it should promote a deeper understanding of the dynamics of cell-cell communication and enable targeted immunotherapy design.

    更新日期:2017-11-23
  • Design of a calix[4]arene-functionalized metal-organic framework probe for highly sensitive and selective monitor of hippuric acid for indexing toluene exposure
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Yaran Du, Xiqian Li, Haijiao Zheng, Xueju Lv, Qiong Jia

    In the present work, a novel metal-organic framework (MOF) fluorescent probe was prepared by post-synthetic modification of MIL-53-NH2(Al) with carboxylatocalix[4]arene (CC[4]A). The introduced CC[4]A could not only enhance the fluorescence performance and the recognition ability of the probe, but also sustain the high stability under UV light and moisture conditions. A method based on the as-synthesized CC[4]A@MIL-53-NH2(Al) probe was established for sensing hippuric acid. The detection limit was determined to be as low as 3.7 μg mL−1. Over the concentration range of 0.005–3 mg mL−1, the calibration curve was obtained with a satisfactory linearity (R2 = 0.993). The method was successfully used for rapid and highly selective direct monitor of hippuric acid in human urine. The sensor had great potential to be used as a simple diagnostic tool for hippuric acid in human urine which is regarded as a biological index of toluene exposure.

    更新日期:2017-11-23
  • Identification of potential sphingomyelin markers for the estimation of hematocrit in dried blood spots via a lipidomic strategy
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Hsiao-Wei Liao, Shu-Wen Lin, Ya-Ting Lin, Ching-Hua Lee, Ching-Hua Kuo

    The dried blood spot (DBS) strategy is a convenient and minimally invasive approach to blood sampling. Due to its various advantages, this sampling technique has drawn significant attention in recent years. Hematocrit (HCT)-associated bias is one of the main obstacles that hinder wider DBS application in clinical practice. An accurate HCT estimation method could help calibrate HCT-associated bias and improve the quantification accuracy. This study used a lipidomics profiling strategy to identify HCT estimation markers using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), which provided advantages including the potential for the simultaneous measurements of target drug and HCT values. Three sphingomyelins (SMs), specifically SM 44:1, SM 44:2, and SM 44:3, were identified as potential HCT estimation markers. The proposed estimation markers were applied to 54 DBS samples collected from two sets of patients. The analytical results revealed that the estimation errors for all of the HCT values were less than 20%, which demonstrated the feasibility of using the proposed markers to estimate the HCT values for the DBS samples. We suggest that the proposed HCT markers could provide a new strategy for HCT estimation with higher convenience using an LC-ESI-MS platform, which could contribute to wider DBS applications in clinical practice. We also demonstrated that lipidomics is a promising strategy for the discovery of HCT estimation markers in DBS samples.

    更新日期:2017-11-23
  • The application of CO2-sensitive AIEgen in studying the synergistic effect of stromal cells and tumor cells in a heterocellular system
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-23
    Didi Chen, Huan Wang, Pai Liu, Linlin Song, Jianbing Shi, Bin Tong, Yuping Dong

    Reciprocal signaling between stromal and tumor cells was believed to contribute to tumor cell proliferation and apoptosis in heterocellular systems. Herein we used the CO2-sensitive AIEgen as bioprobe to study the synergistic effect of stromal cells and tumor cells in a heterocellular system. The experimental results demonstrated that metabolic rates of living tumor cells in the co-culture system were still faster than that of stromal cell through the detection of CO2 generation rate in living cell. All rates were, however, slower than that in homocellular system. It indicated that tumor cells would induce neighboring stromal cells to establish a common protection mechanism against foreign material invasion, which enhanced the cell activity and drug resistance. In addition, tumor cells in solid carcinoma exhibited delayed growth but less apoptosis in co-culture systems. Taken these results together, a bidirectional signaling pathway theory was proposed between tumor and stromal cells in co-culture system and could play a different and important role in anticancer drug molecules designs.

    更新日期:2017-11-23
  • Acoustofluidic hematocrit determination
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Klara Petersson, Ola Jakobsson, Pelle Ohlsson, Per Augustsson, Stefan Scheding, Johan Malm, Thomas Laurell

    Hematocrit (HCT) measurements of blood from patients, blood donors and athletes are routinely performed on a daily basis. These measurements are often performed in centralized hospital labs by whole blood analyzers, which leads to long time-to-result. On site measurements, based on centrifugation can be done, but these assays require manual handling, are slow and can just measure HCT in contrast to the central lab whole blood analyzers. In this work, we present a microfluidic based method to measure HCT in blood samples by acoustic separation of whole blood into discrete regions of plasma and red blood cells. Comparison of the areas of the red blood cell and plasma regions gives an accurate HCT value, with a linear correlation to the centrifugation-based reference method. A readout can be performed within 2 s of acoustic actuation providing a readout accuracy of approximately 3% points (pp) HCT. Additional accuracy can be achieved by extending the acoustic actuation to 20 s, yielding an error of less than 1 pp HCT. This acoustic tool is optimal for integration into a lab-on-a-chip device with in-line measurements of different clinical parameters.

    更新日期:2017-11-23
  • Creasensor: SIMPLE technology for creatinine detection in plasma
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Francesco Dal Dosso, Deborah Decrop, Elena Pérez-Ruiz, Devin Daems, Hannah Agten, Osamah Al-Ghezi, Olivier Bollen, Jolien Breukers, Florian De Rop, Maria Katsafadou, Jens Lepoudre, Linye Lyu, Pieter Piron, Robbe Saesen, Shoera Sels, Rani Soenen, Ellen Staljanssens, Jehan Taraporewalla, Tadej Kokalj, Dragana Spasic, Jeroen Lammertyn

    The lab-on-a-chip (LOC) field has witnessed an excess of new technology concepts, especially for the point-of-care (POC) applications. However, only few concepts reached the POC market often because of challenging integration with pumping and detection systems as well as with complex biological assays. Recently, a new technology termed SIMPLE was introduced as a promising POC platform due to its features of being self-powered, autonomous in liquid manipulations, cost-effective and amenable to mass production. In this paper, we improved the SIMPLE design and fabrication and demonstrated for the first time that the SIMPLE platform can be successfully integrated with biological assays by quantifying creatinine, biomarker for chronic kidney disease, in plasma samples. To validate the robustness of the SIMPLE technology, we integrated a SIMPLE-based microfluidic cartridge with colorimetric read-out system into the benchtop Creasensor. This allowed us to perform on-field validation of the Creasensor in a single-blind study with 16 plasma samples, showing excellent agreement between measured and spiked creatinine concentrations (ICC: 0.97). Moreover, the range of clinically relevant concentrations (0.76–20 mg/dL), the sample volume (5 μL) and time-to-result of only 5 min matched the Creasensor performance with both lab based and POC benchmark technologies. This study demonstrated for the first time outstanding robustness of the SIMPLE in supporting the implementation of biological assays. The SIMPLE flexibility in liquid manipulation and compatibility with different sample matrices opens up numerous opportunities for implementing more complex assays and expanding its POC applications portfolio.

    更新日期:2017-11-23
  • Universal simultaneous multiplex ELISA of small molecules in milk based on dual luciferases
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Xuezhi Yu, Xiya Zhang, Zhanhui Wang, Haiyang Jiang, Ziquan Lv, Jianzhong Shen, Guoliang Xia, Kai Wen

    The enzyme-linked immunosorbent assay (ELISA) has become the most important and widely used rapid detection technology for food safety because of its simple operation, fast speed and high sensitivity. Multiplex synchronous detection is the goal of ELISA that is always pursuing for. However, the reported multiplex ELISAs have not truly realized synchronous detection because of the complex signal generation and collection procedures. Here, we developed a dual-luciferases competitive direct bioluminescent immunoassay (DBL-cdELISA) with only one substrate addition step followed immediately by simultaneous signal acquisition. It is the first report of simultaneous multiplex analysis of small molecules based on microtiter plates and enzymes without any additional steps. The IC50 values for norfloxacin (NOR) and sulfamethazine (SMZ) were 0.051 ng mL−1 and 0.211 ng mL−1, respectively. The results demonstrated that the application of different luciferases and substrates simplified the signal generation and collection procedures and enabled simultaneous detection of small molecules with a simple procedure, high throughput and fast speed, that will be of great significance for the development of multiple assays.

    更新日期:2017-11-23
  • Revealing cooperative binding of polycationic cyclodextrins with DNA oligomers by capillary electrophoresis coupled to mass spectrometry
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Cédric Przybylski, Juan M. Benito, Véronique Bonnet, Carmen Ortiz Mellet, José M. García Fernández

    Gene delivery is critical for the development of nucleic acid-based therapies against a range of severe diseases. The conception of non-viral (semi)synthetic vectors with low cytotoxicity and virus-like efficiency is gathering a lot of efforts, but it represents a fantastic challenge still far from accomplishment. Carbohydrate-based scaffolds offer interesting features towards this end, such as easy availability, relatively cheap cost, tuning properties and a good biocompatibility. The lack of analytical methods providing quantitative and qualitative data on their binding properties with oligonucleotides (DNA/RNA), with a minimal time and sample consumption, represents a limitation for these channels. Here, we attempted to fill the gap by hyphenation of capillary electrophoresis with mass spectrometry (CE-MS). This coupling strategy allows discriminating free and complexed DNA oligomers with cationic cyclodextrins (CDs), determining the stoichiometry where the highest observed is always DNAn: n/3(CD), and unambiguously assigning the partners through m/z detection. Very reliable data were obtained with migration time within 5.5 (standard deviation < 0.5%) and 25 min (standard deviation < 1.1%) for UV and MS detection, respectively. Furthermore, varying the nitrogen/phosphorus ratio (N/P), key parameters relating to the thermodynamics e.g. the micro and macroscopic dissociation constants Kd and KD, respectively (both in low μM range) and the Gibbs free energy ΔG (−16.3 to −26.9 kJ mol−1), and also the cooperativity as Hill number (nH between 0.98 and 15.75) of the supramolecular process can be delineated, providing a unique tool for the high throughput screening and selection of efficient gene delivery carriers.

    更新日期:2017-11-23
  • Self-enhanced PEI-Ru(II) complex with polyamino acid as booster to construct ultrasensitive electrochemiluminescence immunosensor for carcinoembryonic antigen detection
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Yali Yuan, Ling Zhang, Haijun Wang, Yaqin Chai, Ruo Yuan

    In this work, the luminophor tris (4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium (II) dichloride (Ru(dcbpy)32+) was linked to coreactant polyethylenimine (PEI) with effectively shorted distance, forming a novel self-enhanced PEI-Ru(II) complex to fabricate ultrasensitive electrochemiluminescence immunosensor for carcinoembryonic antigen (CEA) detection by using polyamino acid l-cysteine (pL-Cys) as booster for further signal amplification. The light-emitting species (PEI-Ru(II)*) based on intramolecular electron transfer between PEI• and Ru(III) could efficiently amplify the ECL signal of Ru(dcbpy)32+ owing to its benefit for electron transmission. Secondly, the pL-Cys film was fabricated on the glassy carbon electrode by cyclic voltammogram. After that, the pL-Cys acted as a strongly reducing radical could react with PEI-Ru(III) to generate the excited state PEI-Ru(II)*, which further amplify the ECL signal. With the signal amplification factors, the prepared ECL immunosensor exhibited great advantages in simplification, rapidity, stability and selectivity. Furthermore, the linear range for the determination of CEA was from 0.10 pg/mL to 80 ng/mL with a correlation coefficient of 0.9942 and a detection limit of 0.045 pg/mL (S/N = 3).

    更新日期:2017-11-23
  • Self-primer and self-template recycle rolling circle amplification strategy for sensitive detection of uracil-DNA glycosylase activity
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Pingping Zhang, Lei Wang, Haiyan Zhao, Xiaowen Xu, Wei Jiang

    Sensitive and accurate detection of uracil-DNA glycosylase (UDG) activity is available for evaluating and validating their function in uracil base-excision repair (UBER) pathway and clinical diagnosis. Here, a sensitive and accurate method for UDG activity detection was developed on the basis of self-primer and self-template recycle rolling circle amplification (Self-RRCA) strategy. First, an immature template (IT) with a uracil base and an Nt.BbvCI nicking site was designed, which could hybridize with a designed primer to form a pre-amplicon probe (PA probe). Under the action of UDG, the uracil base in the PA probe could be removed to generate an apyrimidinic (AP) site. Then the generated AP site was excised by endonuclease IV (endo IV), making the PA probe form a RCA amplicon through reconformation. The RCA amplicon subsequently was used to trigger the RCA, and after Nt.BbvCI nicking reaction, new amplicons were released to initiate next RCA, constituting a Self-RRCA. In this method, the designed IT was not fully complementary with the primer in the ligation part, which could effectively avoid nonspecific ligation reaction and eventually effectively avoid nonspecific amplification. Compared with the linear RCA, the Self-RRCA exhibited higher amplification efficiency. Due to above advantages, a sensitive and accurate detection method was achieved with a limit of 4.68 × 10−5 U mL−1. Furthermore, the method was adopted to screen the inhibitor of UDG and assay the activity of UDG in HeLa cell lysate. This method will offer a promising analysis tool for further biomedical research of UDG and clinical diagnosis.

    更新日期:2017-11-23
  • A simple desorption atmospheric pressure chemical ionization method for enhanced non-volatile sample analysis
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Md Matiur Rahman, Ting Jiang, Yang Tang, Wei Xu

    In this work, a simple desorption atmospheric pressure chemical ionization (SDAPCI) source is studied and optimized for analyzing a wide variety of samples such as nonvolatile, volatile and biological samples. In this ion source, the heated mass inlet was used for sample desorption, and a solid needle was used to produce a corona discharge for ionization. The utilization of any additional gas or heater is not required in SDAPCI. Due to its high sensitivity, only a small amount of sample is needed. Sample loading and the consequent mass spectrometry analysis process could be easy and fast, which was demonstrated by the analyses of different types of samples ranging from non-volatile to volatile compounds. High-throughput analysis can be performed by SDAPCI source with minimum or no sample preparation.

    更新日期:2017-11-23
  • Relative quantitation of neutral and sialylated N-glycans using stable isotopic labeled d0/d5-benzoyl chloride by MALDI-MS
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Chang Wang, Yike Wu, Liang Zhang, Bi-Feng Liu, Yawei Lin, Xin Liu

    Quantitative analysis of glycans is an emerging field in glycomic research. Herein we present a rapid and effective dual-labeling strategy, in the combination of isotopic derivatization of N-glycosylamine-based glycans by d0/d5-benzoyl chloride and methylamidation of sialic acids, to relatively quantify both neutral and sialylated N-glycans simultaneously by MALDI-MS. The derivatization efficiencies were increased by microwave-accelerated deglycosylation which not only largely reduce the time of glycoprotein deglycosylation but also inhibit the hydrolysis of intermediate glycosylamines produced by PNGase F digestion. Three model glycoproteins, including RNase B, bovine fetuin and IgG from human serum, were applied to validate this technique. Results showed that the glycans from microgram level of glycoprotein can be successfully quantified with high reproducibility and the whole time of analytical procedure was shortened to 4 h. Furthermore, this proposed method was applied for the comparative analysis of N-glycans from serum of healthy donors and multiple myeloma patients. It was found that five N-glycans may be as the potential biomarkers for rapid detection of early multiple myeloma, indicating the feasibility of this strategy in monitoring subtle quantitative differences of serum glycomics.

    更新日期:2017-11-22
  • Novel near-infrared spectrum analysis tool: Synergy adaptive moving window model based on immune clone algorithm
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Shenghao Wang, Yuyan Zhang, Fuyi Cao, Zhenying Pei, Xuewei Gao, Xu Zhang, Yong Zhao

    This paper presents a novel spectrum analysis tool named synergy adaptive moving window modeling based on immune clone algorithm (SA-MWM-ICA) considering the tedious and inconvenient labor involved in the selection of pre-processing methods and spectral variables by prior experience. In this work, immune clone algorithm is first introduced into the spectrum analysis field as a new optimization strategy, covering the shortage of the relative traditional methods. Based on the working principle of the human immune system, the performance of the quantitative model is regarded as antigen, and a special vector corresponding to the above mentioned antigen is regarded as antibody. The antibody contains a pre-processing method optimization region which is created by 11 decimal digits, and a spectrum variable optimization region which is formed by some moving windows with changeable width and position. A set of original antibodies are created by modeling with this algorithm. After calculating the affinity of these antibodies, those with high affinity will be selected to clone. The regulation for cloning is that the higher the affinity, the more copies will be. In the next step, another import operation named hyper-mutation is applied to the antibodies after cloning. Moreover, the regulation for hyper-mutation is that the lower the affinity, the more possibility will be. Several antibodies with high affinity will be created on the basis of these steps. Groups of simulated dataset, gasoline near-infrared spectra dataset, and soil near-infrared spectra dataset are employed to verify and illustrate the performance of SA-MWM-ICA. Analysis results show that the performance of the quantitative models adopted by SA-MWM-ICA are better especially for structures with relatively complex spectra than traditional models such as partial least squares (PLS), moving window PLS (MWPLS), genetic algorithm PLS (GAPLS), and pretreatment method classification and adjustable parameter changeable size moving window PLS (CA-CSMWPLS). The selected pre-processing methods and spectrum variables are easily explained. The proposed method will converge in few generations and can be used not only for near-infrared spectroscopy analysis but also for other similar spectral analysis, such as infrared spectroscopy.

    更新日期:2017-11-22
  • Exploring hyperspectral imaging data sets with topological data analysis
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Ludovic Duponchel

    Analytical chemistry is rapidly changing. Indeed we acquire always more data in order to go ever further in the exploration of complex samples. Hyperspectral imaging has not escaped this trend. It quickly became a tool of choice for molecular characterisation of complex samples in many scientific domains. The main reason is that it simultaneously provides spectral and spatial information. As a result, chemometrics has provided many exploration tools (PCA, clustering, MCR-ALS …) well-suited for such data structure at early stage. However we are today facing a new challenge considering the always increasing number of pixels in the data cubes we have to manage. The idea is therefore to introduce a new paradigm of Topological Data Analysis in order explore hyperspectral imaging data sets highlighting its nice properties and specific features. With this paper, we shall also point out the fact that conventional chemometric methods are often based on variance analysis or simply impose a data model which implicitly defines the geometry of the data set. Thus we will show that it is not always appropriate in the framework of hyperspectral imaging data sets exploration.

    更新日期:2017-11-22
  • Investigations on the selectivity of grafted high performance anion exchangers and the underlying graft mechanism
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Achim Kaltz, Lea Bohra, Jonathan S. Tripp, Andreas Seubert

    Macroporous, monodisperse PS/DVB particles with diameters of 4.0–4.6 μm were functionalized via free radical graft polymerization to create high performance anion exchangers. Varying the amount of monomer from 0 to 10 mmol per 2.0 g PS/DVB allows a control of the column capacity to create columns with capacities up to 350 μeq/column for 100 mm columns. No further increase of the capacity is observed when using more than 6 mmol of the monomer due to a rivaling homopolymerization. With increasing capacity, the exchangers showed increasing selectivity factors of Br− and NO3− in reference to Cl− from 2.4 to 4.3 and 3.5 to 4.6, changing the elution order in the process. At the same time, contradicting the retention model, the selectivity of SO42− did not change with increasing capacity. Analyzing the amount of converted double bonds during functionalization allowed to identify a grafting-onto mechanism, as the amount of converted double bonds ranges from 0% to 52% depending on the amount of monomer used. This information also allowed the calculation of the average chain length, which ranges from 1 to 6 exchanger groups. The average chain length depends on the amount of monomer used, creating higher average chain lengths with higher amounts of monomer. However, it was not possible to link the observed selectivity differences to the average chain lengths of the columns or the influence of the column capacity on the ion exchange mechanism.

    更新日期:2017-11-22
  • Accurate anisotropy recovery from fluorophore mixtures using Multivariate Curve Resolution (MCR)
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Yannick Casamayou-Boucau, Alan G. Ryder

    Anisotropy resolved multidimensional emission spectroscopy (ARMES) provides valuable insights into multi-fluorophore systems like proteins that have complex overlapping emission bands. The method combines multidimensional fluorescence, anisotropy, and chemometrics to facilitate the differentiation of fluorophores with very similar emission properties. Here, we address the critical issue of standardizing the chemometric methods required to accurately extract spectral and anisotropy information from fluorophore mixtures using two standard sample sets: perylene in glycerol, and a mixture of Erythrosin B and Phloxine B with overlapping emission but different anisotropies. We show for the first time how to accurately model component anisotropy using Multivariate Curve Resolution (MCR) from data collected using total synchronous fluorescence scan (TSFS) and Excitation Emission Matrix (EEM) measurement methods. These datasets were selected to avoid the presence of inner filter effects (IFE) or Förster resonance energy transfer (FRET) that would depolarize fluorescence emission or reduce data tri-linearity. This allowed the non-trilinear TSFS data to yield accurate component anisotropy data once modelled using the correct data augmentation strategy, the EEM data proved to be more accurate once optimal constraints (non-negativity and correspondence among species) were employed. For perylene (S2) and Phloxine B which both have very weak anisotropy (<0.06), while the spectral recovery was excellent, the modelled anisotropy values were reasonably accurate (±20% of the real value) because of large relative noise contributions. However, for perylene (S1) and Erythrosin B which have large (>0.2) anisotropies, bilinear and trilinear EEM models built using a total tri-linearity constraint, yielded solutions without any rotational ambiguities and very accurate (±4% of real value) anisotropy values. These sample systems thus provide simple and robust test systems for validating the spectral measurement and chemometric data analysis elements of ARMES.

    更新日期:2017-11-22
  • Hydrophilic polymeric monoliths containing choline phosphate for separation science applications
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-22
    Qiqin Wang, Huihui Wu, Kun Peng, Hanying Jin, Huikai Shao, Yuqiang Wang, Jacques Crommen, Zhengjin Jiang

    In this research, a hydrophilic polymeric monolith containing choline phosphate (CP) was fabricated through the thermally initiated free-radical polymerization of 2-{2-(methacryloyloxy) ethyldimethylammonium}ethyl n-butyl phosphate (MBP) with ethylene dimethacrylate (EDMA) using isopropanol and tetrahydrofuran as the porogenic system. Excellent mechanical strength, permeability, stability and reproducibility were obtained on the optimized poly(MBP-co-EDMA) monolith. Column efficiency as high as 107,500 plates/m was achieved for the analysis of thiourea at a flow velocity of 0.2 mm/s on the monolith. Both hydrophilic and electrostatic interactions were observed for the retention of charged analytes on the poly(MBP-co-EDMA) monolith. It is worth noting that the resulting monolith exhibits higher selectivity and efficiency than the classical 2-(methacryloyloxy)ethyl phosphorylcholine functionalized polymeric monolith for the chromatographic separation of polar analytes. Also, the novel monolithic column was successfully applied to enrich N-glycopeptides from tryptic digest of human IgG. In a word, the versatile MBP functionalized polymeric monolith not only opens up interesting possibilities for reverse zwitterionic CP derivative-based polymeric materials in separation science, but also represents a promising hydrophilic interaction chromatography stationary phase.

    更新日期:2017-11-22
  • Lipid metabolism in mouse embryonic fibroblast cells in response to autophagy induced by nutrient stress
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Sensen Shen, Li Yang, Linnan Li, Yu Bai, Huwei Liu

    Autophagy is of great significance in maintaining cellular homeostasis. Aberrant autophagy has been reported to contribute to the disease aetiology of metabolic syndrome, especially several key lysosomal storage disorders. However, the molecular mechanisms and the correlation between autophagy and lipid metabolism remains unclear. This study was designed and aimed to reveal the alteration of lipid metabolism in response to the autophagy induced by nutrient stress to give new insights into the molecular mechanisms between autophagy and lipid metabolism. An online normal-phase/reversed-phase two-dimensional liquid chromatography-mass spectrometry (NP/RP 2D LC-MS) method was developed to perform the lipidomics analysis of Atg7−/− mouse embryonic fibroblast cells (MEFs) and wild-type MEFs under nutrient stress. 48 and 35 lipid species in wild-type and Atg7−/− MEFs respectively finally meet the screening criteria with p-value less than 0.05 and fold change more than 1.5 in response to nutrient stress. Their alterations indicated that autophagy participated lipid metabolism to generate energy and form autophagosomes with significantly increased free fatty acids and glycerophospholipids, which protected wild-type MEFs from serious damages and delayed cell death. However, in Atg7−/− MEFs, due to the inhibition of autophagy, lipids were continuously consumed and cells suffered from damages even death. These results illustrated the close relationship between autophagy and lipid metabolism comprehensively and revealed diverse lipid targets for the investigation of autophagy.

    更新日期:2017-11-15
  • Development of an LC-ESI(-)-MS/MS method for the simultaneous quantification of 35 isoprostanes and isofurans derived from the major n3- and n6-PUFAs
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Katharina M. Rund, Annika I. Ostermann, Laura Kutzner, Jean-Marie Galano, Camille Oger, Claire Vigor, Sabine Wecklein, Nina Seiwert, Thierry Durand, Nils Helge Schebb

    Misregulation of oxidative and antioxidative processes in the organism – oxidative stress – contributes to the pathogenesis of different diseases, e.g. inflammatory or neurodegenerative diseases. Oxidative stress leads to autoxidation of polyunsaturated fatty acids giving rise to prostaglandin-like isoprostanes (IsoP) and isofurans (IsoF). On the one hand they could serve as biomarker of oxidative stress and on the other hand may act as lipid mediators, similarly as the enzymatically formed oxylipins. In the present paper we describe the development of an LC-ESI(-)-MS/MS method allowing the parallel quantification of 27 IsoP and 8 IsoF derived from 6 different PUFA (ALA, AA, EPA, AdA, DPA, DHA) within 12 min. The chromatographic separation was carried out on a RP-C18 column (2.1 × 150 mm, 1.8 μm) yielding narrow peaks with an average width at half maximum of 3.3–4.2 s. Detection was carried out on a triple quadrupole mass spectrometer operating in selected reaction monitoring mode allowing the selective detection of regioisomers. The limit of detection ranged between 0.1 and 1 nM allowing in combination to solid phase extraction the detection of IsoP and IsoF at subnanomolar concentration in biological samples. The method was validated for human plasma showing high accuracy and precision. Application of the approach on the investigation of oxidative stress in cultured cells indicated a distinct pattern of IsoP and IsoF in response to reactive oxygen species which warrants further investigation.The described method is not only the most comprehensive approach for the simultaneous quantification of IsoP and IsoF, but it was also integrated in a targeted metabolomics method (Ostermann et al. (2015) Anal Bioanal Chem) allowing the quantification of in total 164 oxylipins formed enzymatically and non-enzymatically within 30.5 min.

    更新日期:2017-11-15
  • Development of a GC/MS method for the qualitative and quantitative analysis of mixtures of free fatty acids and metal soaps in paint samples
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Jacopo La Nasa, Francesca Modugno, Matteo Aloisi, Anna Lluveras Tenorio, Ilaria Bonaduce

    In this paper we present a new analytical GC/MS method for the analysis of mixtures of free fatty acids and metal soaps in paint samples. This approach is based on the use of two different silylating agents: N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS).Our experimentation demonstrated that HMDS does not silylate fatty acid carboxylates, so it can be used for the selective derivatization and GC/MS quantitative analysis of free fatty acids. On the other hand BSTFA is able to silylate both free fatty acids and fatty acids carboxylates. The reaction conditions for the derivatization of carboxylates with BSTFA were thus optimized with a full factorial 32 experimental design using lead stearate and lead palmitate as model systems. The analytical method was validated following the ICH guidelines. The method allows the qualitative and quantitative analysis of fatty acid carboxylates of sodium, calcium, magnesium, aluminium, manganese, cobalt, copper, zinc, cadmium, and lead and of lead azelate. In order to exploit the performances of the new analytical method, samples collected from two reference paint layers, from a gilded 16th century marble sculpture, and from a paint tube belonging to the atelier of Edvard Munch, used in the last period of his life (1916–1944), were characterized.

    更新日期:2017-11-14
  • Applying quantitative metabolomics based on chemical isotope labeling LC-MS for detecting potential milk adulterant in human milk
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Dorothea Mung, Liang Li

    There is an increasing demand for donor human milk to feed infants for various reasons including that a mother may be unable to provide sufficient amounts of milk for their child or the milk is considered unsafe for the baby. Selling and buying human milk via the Internet has gained popularity. However, there is a risk of human milk sold containing other adulterants such as animal or plant milk. Analytical tools for rapid detection of adulterants in human milk are needed. We report a quantitative metabolomics method for detecting potential milk adulterants (soy, almond, cow, goat milk and infant formula) in human milk. It is based on the use of a high-performance chemical isotope labeling (CIL) LC-MS platform to profile the metabolome of an unknown milk sample, followed by multivariate or univariate comparison of the resultant metabolomic profile with that of human milk to determine the differences. Using dansylation LC-MS to profile the amine/phenol submetabolome, we could detect an average of 4129 ± 297 (n = 9) soy metabolites, 3080 ± 470 (n = 9) almond metabolites, 4256 ± 136 (n = 18) cow metabolites, 4318 ± 198 (n = 9) goat metabolites, 4444 ± 563 (n = 9) infant formula metabolites, and 4020 ± 375 (n = 30) human metabolites. This high level of coverage allowed us to readily differentiate the six different types of samples. From the analysis of binary mixtures of human milk containing 5, 10, 25, 50 and 75% other type of milk, we demonstrated that this method could be used to detect the presence of as low as 5% adulterant in human milk. We envisage that this method could be applied to detect contaminant or adulterant in other types of food or drinks.

    更新日期:2017-11-14
  • Homochiral porous organic cage used as stationary phase for open tubular capillary electrochromatography
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Jun-Hui Zhang, Peng-Jing Zhu, Sheng-Ming Xie, Min Zi, Li-Ming Yuan

    Porous organic molecular cages, as a new type of porous materials, have in recent years attracted a tremendous amount of attention for their potential applications. However, to the best of our knowledge, there has been no attempt to utilize porous organic molecular cages as stationary phases in capillary electrochromatography (CEC). We report herein the use of a homochiral porous organic cage (POC) (CC3-R) as a stationary phase in open tubular capillary electrochromatography (OT-CEC) for the separation of chiral compounds and positional isomers. The column was fabricated using CC3-R as the stationary phase by a static coating method. Separation of furoin, benzoin, and alprenlol were achieved on the CC3-R coated column, with the highest resolution value (Rs = 3.35) for the separation of benzoin. The influences of pH and buffer concentration on separation have been investigated. Besides, the CC3-R column also exhibited good selectivity for the separation of positional isomers, including those of nitrophenols, phenylenediamines, aminophenols, and ionones. The run-to-run (n = 5), day-to-day (n = 5), column-to-column (n = 3), and batch-to-batch (n = 3) relative standard deviations (RSDs) for the analyte migration time were in the range of 0.5–1.5%, 0.2–1.8%, 1.2–2.1% and 1.5–2.8%, respectively. The RSDs for the migration time and enantioselectivity of the analyte were less than 5.9% and 2.2% (inter-day, n = 5) after a week of continuous use. This work also indicates that porous organic molecular materials are promising for enantioseparation in CEC and look set to become more attractive in separation science.

    更新日期:2017-11-14
  • Effects of structure on the performance of latex nanoparticles as a pseudostationary phase in electrokinetic chromatography
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Jesse S. Hyslop, Julie R. McGettrick, Leah M.G. Hall, Hungngai Chuk, Christopher P. Palmer

    The fundamental relationships between the structure and chemistry of latex nanoparticles synthesized by reversible addition fragmentation chain transfer (RAFT) controlled living polymerization and their subsequent performance as pseudostationary phases (PSP) is reported in this paper. RAFT enables the rational optimization of latex nanoparticle pseudostationary phases and control of the behavior of the PSP. Nanoparticles comprised of amphiphilic diblock copolymers of 2-acrylamido-2-methylpropane sulfonic acid-derived ionic/hydrophilic blocks and butyl- ethyl- or methyl-acrylate-derived hydrophobic blocks were synthesized in two sizes. The mobility, methylene selectivity, and efficiency of each of the six pseudostationary phases are reported, as well as the relationship between monomer quantity and NP size. Linear solvation energy relationships are reported and compared to SDS micelles and previous nanoparticle pseudostationary phases. The solvation characteristics and selectivity of nanoparticle pseudostationary phases is shown to be affected primarily by the structure of the hydrophobic copolymer block. Butyl acrylate nanoparticles 17 nm in diameter are found to provide the best overall separation performance with over 500 thousand theoretical plates generated in 6 min separations.

    更新日期:2017-11-14
  • Quantification ethyl carbamate in wines using reaction-assisted-extraction with 9-xanthydrol and detection by heart-cutting multidimensional gas chromatography-mass spectrometry
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Qiqi Tu, Wanshu Qi, Junbo Zhao, Li Zhang, Yinlong Guo

    9-Xanthydrol was introduced as an assisted-extraction-reagent to quantify ethyl carbamate (EC) in wines by heart-cutting multidimensional gas chromatography coupled with mass spectrometry (MDGC-MS). 9-Xanthydrol could help to increase the extraction efficiency, because it could react with ethyl carbamate to form the low-polar product, which facilitated the transfer of ethyl carbamate into organic phase. Then the reaction product was decomposed in high temperature, so ethyl carbamate could be obtained again in injector port. Heart-cutting multidimensional gas chromatography coupled with mass spectrometry was used not only for avoiding 9-xanthydrol interference but also for getting a larger volume injector, higher sensitivity and lower limit of detection. The method was optimized and validated in terms of sample volume, sodium chloride, the acid concentration, the 9-xanthydrol concentration and the reaction time. Good linear relationship (R2 = 0.9998) over the concentration range of 2.00 μg L−1 - 200.00 μg L−1 was obtained. The limit of detection (LOD, 0.02 μg L−1) and quantification (LOQ, 0.10 μg L−1) were lower than previously reported. The RSDs of precision (repeatability and reproducibility) were lower than 8.15%, and the recovery (96.17–99.25%) and accuracy (99.21–110.93%) were validated as well. This methodology was applied to the quantification of ethyl carbamate in several different fermented wines with values ranging from 13.05 to 155.20 μg L−1.

    更新日期:2017-11-14
  • Carbon fiber brush electrode as a novel substrate for atmospheric solids analysis probe (ASAP) mass spectrometry: Electrochemical oxidation of brominated phenols
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Jana Skopalová, Petr Barták, Petr Bednář, Hana Tomková, Tomáš Ingr, Iveta Lorencová, Pavla Kučerová, Roman Papoušek, Lucie Borovcová, Karel Lemr

    A carbon fiber brush electrode (CFBE) was newly designed and used as a substrate for both controlled potential electrolysis and atmospheric solids analysis probe (ASAP) mass spectrometry. Electropolymerized and strongly adsorbed products of electrolysis were directly desorbed and ionized from the electrode surface. Electrochemical properties of the electrode investigated by cyclic voltammetry revealed large electroactive surface area (23 ± 3 cm2) at 1.3 cm long array of carbon fibers with diameter 6–9 μm. Some products of electrochemical oxidation of pentabromophenol and 2,4,6-tribromophenol formed a compact layer on the carbon fibers and were analyzed using ASAP. Eleven new oligomeric products were identified including quinones and biphenoquinones. These compounds were not observed previously in electrolyzed solutions by liquid or gas chromatography/mass spectrometry. The thickness around 58 nm and 45 nm of the oxidation products layers deposited on carbon fibers during electrolysis of pentabromophenol and 2,4,6-tribromophenol, respectively, was estimated from atomic force microscopy analysis and confirmed by scanning electron microscopy with energy-dispersive X-ray spectroscopy measurements.

    更新日期:2017-11-14
  • Optimization of mass spectrometric parameters improve the identification performance of capillary zone electrophoresis for single-shot bottom-up proteomics analysis
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-14
    Zhenbin Zhang, Norman J. Dovichi

    The effects of MS1 injection time, MS2 injection time, dynamic exclusion time, intensity threshold, and isolation width were investigated on the numbers of peptide and protein identifications for single-shot bottom-up proteomics analysis using CZE-MS/MS analysis of a Xenopus laevis tryptic digest. An electrokinetically pumped nanospray interface was used to couple a linear-polyacrylamide coated capillary to a Q Exactive HF mass spectrometer. A sensitive method that used a 1.4 Th isolation width, 60,000 MS2 resolution, 110 ms MS2 injection time, and a top 7 fragmentation produced the largest number of identifications when the CZE loading amount was less than 100 ng. A programmable autogain control method (pAGC) that used a 1.4 Th isolation width, 15,000 MS2 resolution, 110 ms MS2 injection time, and top 10 fragmentation produced the largest number of identifications for CZE loading amounts greater than 100 ng; 7218 unique peptides and 1653 protein groups were identified from 200 ng by using the pAGC method. The effect of mass spectrometer conditions on the performance of UPLC-MS/MS was also investigated. A fast method that used a 1.4 Th isolation width, 30,000 MS2 resolution, 45 ms MS2 injection time, and top 12 fragmentation produced the largest number of identifications for 200 ng UPLC loading amount (6025 unique peptides and 1501 protein groups). This is the first report where the identification number for CZE surpasses that of the UPLC at the 200 ng loading level. However, more peptides (11476) and protein groups (2378) were identified by using UPLC-MS/MS when the sample loading amount was increased to 2 μg with the fast method. To exploit the fast scan speed of the Q-Exactive HF mass spectrometer, higher sample loading amounts are required for single-shot bottom-up proteomics analysis using CZE-MS/MS.

    更新日期:2017-11-14
  • A high sensitive and contaminant tolerant matrix for facile detection of membrane proteins by matrix-assisted laser desorption/ionization mass spectrometry
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-13
    Sheng Wang, Chunsheng Xiao, Liyan Jiang, Ling Ling, Xuesi Chen, Xinhua Guo

    Despite the significance of membrane proteins (MPs) in biological system is indisputable, their specific natures make them notoriously difficult to be analyzed. Particularly, the widely used Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) prefers analyses of hydrophilic cytosolic proteins and has a limited ionization efficiency towards hydrophobic MPs. Herein, a hydrophobic compound (E)-propyl α-Cyano-4-Hydroxyl Cinnamylate (CHCA-C3), a propyl-esterified derivative of α-cyano-4-hydroxycinnamic acid (CHCA), was applied as a contaminant tolerant matrix for high sensitivity MALDI-MS analyses of MPs. With CHCA-C3, the detection limits of hydrophobic peptides were 10- to 100-fold better than those using CHCA. Furthermore, high quality of spectra could be achieved in the presence of high concentration of chaotropes, salts and detergents, as well as human urinary and serum environment. Also, CHCA-C3 could generate uniform sample distribution even in the presence of contaminants. This high contaminant-resistance was revealed to be ascribed to the enhanced hydrophobicity of CHCA-C3 with a lower affinity towards hydrophilic contaminants. The application of CHCA-C3 is further demonstrated by the analysis of trypsin/CNBr digests of bacteriorhodopsin containing seven transmembrane domains (TMDs), which dramatically increased numbers of identified hydrophobic peptides in TMDs and sequence coverage (∼100%). Besides, a combined method by using CHCA-C3 with fluoride solvent and a patterned paraffin plate was established for analysis of integral MPs. We achieved a low detection limit of 10 fmol for integral bacteriorhodopsin, which could not be detected using traditional matrices such as 3,5-dimethoxy-4-hydroxycinamic acid, 2,5-dihydroxyacetophenone even at sample concentration of 10 pmol.

    更新日期:2017-11-14
  • Highly sensitive MicroRNA 146a detection using a gold nanoparticle–based CTG repeat probing system and isothermal amplification
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-13
    Binh Huy Le, Young Jun Seo

    We have developed a gold nanoparticle (AuNP)–based CTG repeat probing system displaying high quenching capability and combined it with isothermal amplification for the detection of miRNA 146a. This method of using a AuNP-based CTG repeat probing system with isothermal amplification allowed the highly sensitive (14 aM) and selective detection of miRNA 146a. A AuNP-based CTG repeat probing system having a hairpin structure and a dTF fluorophore exhibited highly efficient quenching because the CTG repeat–based stable hairpin structure imposed a close distance between the AuNP and the dTF residue. A small amount of miRNA 146a induced multiple copies of the CAG repeat sequence during rolling circle amplification; the AuNP-based CTG repeat probing system then bound to the complementary multiple-copy CAG repeat sequence, thereby inducing a structural change from a hairpin to a linear structure with amplified fluorescence. This AuNP-based CTG probing system combined with isothermal amplification could also discriminate target miRNA 146a from one- and two-base-mismatched miRNAs (ORN 1 and ORN 2, respectively). This simple AuNP-based CTG probing system, combined with isothermal amplification to induce a highly sensitive change in fluorescence, allows the detection of miRNA 146a with high sensitivity (14 aM) and selectivity.

    更新日期:2017-11-14
  • Enzyme-assisted polymer film degradation-enabled biomolecule sensing with poly (N-isopropylacrylamide)-based optical devices
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-11
    Wei Zhang, Menglian Wei, Wildemar S.P. Carvalho, Michael J. Serpe

    A biosensor for mouse Immunoglobulin G (IgG) was generated from responsive polymer-based interference filters (etalons). To accomplish this, an excess amount of alkaline phosphatase-modified goat anti-mouse IgG (AP-GAM, F(ab’)2 fragment specific to mouse IgG) was added to mouse IgG, and allowed to react for some time. After a given reaction time, the bound AP-GAM could be isolated from the unbound, excess AP-GAM by addition of goat anti-mouse IgG (Fc fragment specific)-modified magnetic microspheres (GAM-M) that bind the mouse IgG bound to AP-GAM. After application of a magnetic field, the free, unbound AP-GAM was isolated from the mixture and exposed to an etalon that has its upper Au surface modified with phosphate-containing polymer that can be degraded by AP-GAM. By the phosphate-containing polymer being degraded by the excess AP-GAM, the cleaved phosphate groups can diffuse into the interference filter's active polymer layer that yields a change in the optical properties that can be related to the amount of IgG in the sample. This concept is extremely straightforward to implement, and can be modified to detect a variety of other analytes of interest.

    更新日期:2017-11-11
  • Review on microfluidic paper-based analytical devices towards commercialisation
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-11
    Tugce Akyazi, L. Basabe-Desmonts, Fernando Benito-Lopez

    Paper-based analytical devices introduce an innovative platform technology for fluid handling and analysis, with wide range of applications, promoting low cost, ease of fabrication/operation and equipment independence. This review gives a general overview on the fabrication techniques reported to date, revealing and discussing their weak points as well as the newest approaches in order to overtake current mass production limitations and therefore commercialisation. Moreover, this review aims especially to highlight novel technologies appearing in literature for the effective handling and controlling of fluids. The lack of flow control is the main problem of paper-based analytical devices, which generates obstacles for marketing and slows down the transition of paper devices from the laboratory into the consumers' hands.

    更新日期:2017-11-11
  • Potential of saliva steroid profiling for the detection of endogenous steroid abuse: Reference thresholds for oral fluid steroid concentrations and ratios
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-11
    Michael Polet, Laurie De Wilde, Pieter Van Renterghem, Wim Van Gansbeke, Peter Van Eenoo

    Urine and blood samples are the primary matrices for the detection of exogenous substances in doping control and toxicology. Although these matrices are, in general, very suitable for a wide range of substances, they do show some issues in particular cases. Here, alternative matrices may provide an answer. In this work, a quantitative method for steroid profiling (5 endogenous steroids and their ratios) in oral fluid was developed and validated. In total, 826 saliva samples were analyzed, and inter-individual reference population thresholds for saliva steroid profile parameters were set up. Alterations of this steroid profile after administration of naturally occurring anabolic androgenic steroids (e.g. testosterone (T) or dehydroepiandrosterone (DHEA)) were investigated. In addition, intra-individual short and long-term natural fluctuations were investigated. For longitudinal monitoring in oral fluid, steroid profile ratios (e.g., T/DHEA) were superior to absolute concentrations due to lower susceptibility towards the diurnal pattern. For the detection of a transdermal application of T, the salivary parameter T/DHEA proved to have the highest sensitivity. In contrast with the current screening procedures in urine, there is no need for an additional expensive and time-consuming isotope ratio mass spectrometry confirmation procedure to unequivocally attribute the elevated parameter to an exogenous origin.

    更新日期:2017-11-11
  • Using magnetic beads and signal amplifiers to produce short and simple immunoassays: Application to MMP-9 detection in plasma samples
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-10
    Manel Ben Ismail, Erica de la Serna, Gisela Ruiz-Vega, Teresa García-Berrocoso, Joan Montaner, Mohammed Zourob, Ali Othmane, Eva Baldrich

    Magnetic beads (MB) and signal amplifiers, such as horseradish peroxidase polymers (poly-HRP), have been used before for the production of highly sensitive immunoassays. However, most of the examples reported previously entailed long and tedious multi-step procedures, which were not necessarily shorter or simpler than classical paths such as Enzyme-Linked Immunosorbent Assay (ELISA). Here, instead of exploiting the combination of MB and poly-HRP to ameliorate sensitivity, we show that they conform a powerful tool that can be used to shorten the incubation times, which allows optimizing extremely simple, fast and efficient immunoassays with minimal technical requirements. In order to do so, here we used the highly sensitive and specific pair of antibodies of a commercial ELISA kit to optimize a magneto-ELISA for the detection of matrix metallopeptidase 9 (MMP-9). Three signal amplifiers were then tested and the best performing one was implemented in the magneto-assay to shorten the incubation times and improve assay performance. As we show, the shortened magneto-assay could be carried out in about 35 min, which included two 5-min incubations, washing, and incubation with enzyme substrate for 20 min before colorimetric detection. Moreover, the quantification of MMP-9 provided by the shortened assay in 12 plasma samples collected from patients was comparable to that generated by the 5-h ELISA, which was 8.5 times longer.

    更新日期:2017-11-11
  • Regulating immobilization performance of metal-organic coordination polymers through pre-coordination for biosensing
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-10
    Hua Yang, Xin Qi, Xinquan Wang, Xiangyun Wang, Qiang Wang, Peipei Qi, Zhiwei Wang, Xiahong Xu, Yingchun Fu, Shouzhuo Yao

    We propose a method for regulating biomolecules immobilization performance of metal-organic coordination polymers (MOCPs) through pre-coordination for highly sensitive biosensing. 2,5-dimercapto-1,3,4-thiadiazole (DMcT) was used as organic monomers. Firstly, using CuCl2 as the source of metal ions to form short oligomers with DMcT (MOCPsCu), which can regulate the length of ligands through pre-coordination. Then exploiting NaAuCl4 as the source of Au ions to coordinate both short oligomers and biomolecules (MOCPsCu+Au), since Au ions can coordinate with both N and S atoms. Through controlling the concentration of CuCl2, oligomers with desired length could be readily obtained to prepare MOCPsCu+Au framework with controllable porosity and enzyme entrapment efficiency. Thus MOCPsCu+Au offers several advantages including improved mass transfer efficiency and biocatalytic sensitivity than conventional MOCPs using single metal ions. Glucose oxidase (GOx) was used as the representative biomolecule, the entrapment ratio of enzyme in MOCPsCu+Au case reached an extreme value of 100%. These MOCPsCu+Au biocomposites modified electrode also showed greatly enhanced biocatalytic sensitivity (127 μA cm−2 mM−1) and very low detection limit (58 nM), compared with those reported analogues. The new materials/strategy may create new avenue to regulate the performance of ligand-constructed polymers and their composites for entrapment-based applications.

    更新日期:2017-11-11
  • Water-based alkyl ketene dimer ink for user-friendly patterning in paper microfluidics
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-10
    Nurul Nadiah Hamidon, Yumiao Hong, Gert I.J. Salentijn, Elisabeth Verpoorte

    We propose the use of water-based alkyl ketene dimer (AKD) ink for fast and user-friendly patterning of paper microfluidic devices either manually or using an inexpensive XY-plotter. The ink was produced by dissolving hydrophobic AKD in chloroform and emulsifying the solution in water. The emulsification was performed in a warm water bath, which led to the evaporation of chloroform. Subsequent rapid cooling led to the final product, an aqueous suspension of fine AKD particles. The effects of surfactant and AKD concentrations, emulsification procedure, and cooling approach on final ink properties are presented, as along with an optimized protocol for its formulation. This hydrophobic agent was applied onto paper using a plotter pen, after which the paper was heated (cured) to allow spreading of AKD molecules and chemical bonding with cellulose. A paper surface patterned with the ink (10 g L−1 AKD) yielded a contact angle of 135.6° for water. Unlike organic solvent-based solutions of AKD, this AKD ink does not require a fume hood for its use. Moreover, it is compatible with plastic patterning tools, due to the effective removal of chloroform in the production process to less than 2% of the total volume. Furthermore, this water-based ink is easy to prepare and use. Finally, the AKD ink can also be used for the fabrication of so-called selectively permeable barriers for use in paper microfluidic networks. These are barriers that stop the flow of water through paper, but are permeable to solvents with lower surface energies. We applied the AKD ink to confine and preconcentrate sample on paper, and demonstrated the use of this approach to achieve higher detection sensitivities in paper spray ionization-mass spectrometry (PSI-MS). Our patterning approach can be employed outside of the analytical lab or machine workshop for fast prototyping and small-scale production of paper-based analytical tools, for use in limited-resource labs or in the field.

    更新日期:2017-11-11
  • Ultrasensitive flexible FET-type aptasensor for CA 125 cancer marker detection based on carboxylated multiwalled carbon nanotubes immobilized onto reduced graphene oxide film
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-10
    Samira Mansouri Majd, Abdollah Salimi

    The development of a novel flexible and ultrasensitive aptasensor based on carboxylated multiwalled carbon nanotubes (MWCNTs)/ reduced graphene oxide-based field effect transistor (FET) has been reported for label-free detection of the ovarian cancer antigen 125 (CA125). The fabricated sensor has a straightforward design based on the noncovalent attachment of MWCNTs/aptamer conjugated onto few layers reduced graphene oxide nanosheets and its integration with poly-methyl methacrylate (PMMA) as a suitable platform for designing flexible field-effect transistors. The surface properties of the aptasensor were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Under optimal conditions, the proposed aptasensor exhibited a wide linear dynamic range for CA125 (1.0 × 10−9-1.0 U/mL) with a low detection limit of 5.0 × 10−10 U/mL. The proposed aptasensor was also successfully applied to detect CA125 in real human serum samples. Furthermore, sensor flexibility is also a challenging area in chemical and biological sensors, especially for portable, wearable, or even implantable sensors, so, the reduced graphene oxide-based FET-type aptasensor showed bendable flexibility on the PMMA substrate. In addition, the aptasensor exhibited high sensitivity, selectivity, stability and reproducibility which offers great promise as a high performance and flexible FET-type aptasensor to detect CA125 and other cancer biomarkers in clinical samples and biological fluids.

    更新日期:2017-11-11
  • The effect of hematocrit on solid-phase microextraction ☆
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-10
    Nathaly Reyes-Garcés, Md Nazmul Alam, Janusz Pawliszyn

    Solid-phase microextraction (SPME) is an approach to sample preparation that has demonstrated its appropriateness for isolating/enriching analytes present in complex biofluids with minimum sample pre-treatment. Several prior in vitro and in vivo studies have used SPME to monitor the concentrations of various drugs and metabolites in blood samples. In this work, we present the results of an investigation into how various levels of hematocrit (Hct) affect SPME recoveries. The matrices for this study consisted of whole blood samples that had been adjusted at three different Hct levels (20%, 45%, and 70%), and the selected model compounds were drugs with different physicochemical characteristics (log P range from 0.33 to 6.36). In addition, two experimental setups were employed to conduct the extractions: hydrophilic lipophilic balanced (HLB) coated SPME devices (HLB-D) at 1500 rpm (vortex agitation), and mixed mode SPME fibres (MM-F) at 400 rpm (orbital shaking agitation). Our results demonstrated that the Hct effect in SPME is dependent on the analytes of interest, and that different outcomes can be attained by altering experimental conditions, such as coating type, convection, and extraction time. Interestingly, a target compound's relative affinity for the matrix components and for the coating material proved to be one of the main factors that determine the final effect that different erythrocyte levels have on SPME recoveries. Finally, although the Hct content affects each analyte differently and the final Hct effect depends on the experimental parameters, matrix variability can be corrected by using appropriate internal standards, thereby resulting in correct quantification.

    更新日期:2017-11-11
  • Enhanced fluidity liquid chromatography of inulin fructans using ternary solvent strength and selectivity gradients
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Raffeal Bennett, Susan V. Olesik

    The value of exploring selectivity and solvent strength ternary gradients in enhanced fluidity liquid chromatography (EFLC) is demonstrated for the separation of inulin-type fructans from chicory. Commercial binary pump systems for supercritical fluid chromatography only allow for the implementation of ternary solvent strength gradients which can be restrictive for the separation of polar polymeric analytes. In this work, a custom system was designed to extend the capability of EFLC to allow tuning of selectivity or solvent strength in ternary gradients. Gradient profiles were evaluated using the Berridge function (RF1), normalized resolution product (NRP), and gradient peak capacity (Pc). Selectivity gradients provided the separation of more analytes over time. The RF1 function showed favor to selectivity gradients with comparable Pc to that of solvent strength gradients. NRP did not strongly correlate with Pc or RF1 score. EFLC with the hydrophilic interaction chromatography, HILIC, separation mode was successfully employed to separate up to 47 fructan analytes in less than 25 min using a selectivity gradient.

    更新日期:2017-11-10
  • A highly sensitive gold nanoparticle-based electrochemical aptasensor for theophylline detection
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Xifeng Chen, Zhenzhen Guo, Yuguo Tang, Ying Shen, Peng Miao

    Theophylline is a common bronchodilator for the treatment of diseases like asthma, bronchitis and emphysema. However, it should be strictly used and monitored due to its toxicity when the concentration is above certain levels. In this work, an electrochemical biosensor for theophylline detection is proposed by recognition of RNA aptamer and gold nanoparticle (AuNP)-based amplification technique. First, RNA aptamer is splitted into two single-stranded RNA probes. One is hybridized with DNA tetrahedron and the resulted nanostructure is then immobilized onto a gold electrode; the other is modified on the surface of AuNPs which is also labeled with methylene blue (MB) as electrochemical species. The recognition process between the two RNA probes and theophylline causes the localization of AuNPs and the enrichment of MB on the electrode interface. A significant electrochemical response is thus generated which is related to the concentration of initial theophylline. This proposed aptasensor shows excellent sensitivity and selectivity which could also be applied in quantitatively detection of theophylline in serums samples.

    更新日期:2017-11-10
  • Development and validation of a LC/MS-based method for the measurement of intracellular superoxide anion
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Ze-Yuan Wang, Yi Li, Wen-Qi Chang, Jia-Yi Zheng, Ping Li, Li-Fang Liu, Gui-Zhong Xin

    Superoxide anion (O2.-), as the first generated reactive oxygen species (ROS), has been considered to be highly deleterious to cell functions. The measurement of intracellular O2.- level is of great importance to uncover its roles in a variety of oxidative damage diseases. Hydroethidium (HE) fluorescence-based method is dominating intracellular O2.- assay by monitoring the unique product 2-OH-E+ of HE/O2.- reaction. However, the avoid-less cross-interference of red fluorescence limited its ability to provide trustworthy information on intracellular O2.- formation. By the detection of 2-OH-E+, we herein developed and validated an improved LC/MS-based method for the measurement of intracellular O2.-. Firstly, we demonstrated the proportionality of HE/O2.- reaction. Secondly, ungerimine was used as internal standard to eliminate daily basis and matrix effect in the LC/MS-based detection of 2-OH-E+. Afterward, the total protein concentration was utilized for cell number normalization. Accordingly, an equation was further proposed to calculate the relative abundance (RA) of intracellular O2.-. Finally, the developed method has been successfully utilized to evaluate the inhibitory effects of natural compounds on O2.- generation, the result of which was validated by the HE-based fluorescent measurement. Compared with the fluorescent measurement, the LC/MS-based intracellular O2.- assay method is more sensitive, selective and accurate.

    更新日期:2017-11-10
  • QCM-based rapid detection of PCR amplification products of Ehrlichia canis
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Kespunyavee Bunroddith, Nareerat Viseshakul, Kosum Chansiri, Peter Lieberzeit

    Ehrlichia canis is an intracellular parasitic bacterium and arthropod-borne pathogen that receives growing attention, because it leads to increasing morbidity and mortality in animals. It does so by causing canine monocytotropic ehrlichiosis (CME). Infected canines may lack obvious clinical signs and stay in chronic stage. Herein we report a rapid screening method based on PCR assay combined with quartz crystal microbalance (QCM) to design a DNA sensor for detecting E. canis in early stages of infection. The test relies on DNA amplification of target nucleotide sequences via PCR followed by detecting DNA-DNA hybridization using QCM. The approach did not result in any cross-hybridization toward other blood bacteria or parasites in dogs, such as Anaplasma platys, Babesia canis and Trypanosoma spp, but turned out selective for the target species. The limit of detection of QCM was as low as 4.1 × 109 molecules/μl of 289 bp E. canis PCR products corresponding to 22 copy numbers/μl of E. canis. Furthermore, the technique is also simple, does not require complicated equipment and can in principle be reused.

    更新日期:2017-11-10
  • Rapid differentiation of Ganoderma species by direct ionization mass spectrometry
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Ho-Yi Wong, Melody Yee-Man Wong, Bin Hu, Pui-Kin So, Chi-On Chan, Daniel Kam-Wah Mok, Zhong-Ping Yao

    In this study, direct ionization mass spectrometry (DI-MS) has been developed for rapid differentiation of Ganoderma (known as Lingzhi in Chinese), a very popular and valuable herbal medicine. Characteristic mass spectra can be generated by DI-MS directly from the raw herbal medicines with the application of a high voltage and solvents. Rapid differentiation of the Ganoderma species that are officially stated in the Chinese pharmacopoeia from easily confused Ganoderma species could be achieved based on this method, as the acquired DI-MS spectra showed that ganoderic acids, the major active components of Ganoderma, could be found only in the official Ganoderma species but not in the confused Ganoderma species. In addition, classification of wild and cultivated Ganoderma and potential differentiation of Ganoderma from different geographical locations could be accomplished based on principal component analysis (PCA) or hierarchical clustering analysis (HCA). The method is rapid, simple and reproducible, and can be further extended to analysis of other herbal medicines.

    更新日期:2017-11-10
  • Needle-based sampling coupled with colorimetric reaction catalyzed by layered double hydroxide peroxidase mimic for rapid detection of the change of d-glucose levels with time in bananas
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Wei Shen, Jun Sun, Jowy Yi Hoong Seah, Lei Shi, Sheng Tang, Hian Kee Lee

    For analyte detection in raw fruits, the conventional sample pretreatment method usually involves mashing (blending or homogenization), extraction, and dilution. This process is time-consuming, solvent-intensive and laborious. Usually, there is also a lot wastage with multiple fruits being combined into composite samples. In this work, a new micro-sampling approach based on a syringe needle is developed; it was coupled with micro liquid-phase extraction to determine and quantify d-glucose in bananas. This sampling and extraction approach was quick, easy and required only minimal use of solvent. The d-glucose in the extracted banana flesh was first oxidized enzymatically with glucose oxidase. The resulting peroxide was then detected colorimetrically via oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of a catalyst. The latter, consisting of an iron (III)–nickel (II) layered double hydroxide (LDH[NiII-FeIII]) was synthesized in this work for the purpose. The results of this new detection method for d-glucose in fruits provided low limits of detection (0.025 μg/mL), wide linear range (0.1–3000 μg/mL) and good linearity (r2 = 0.9998). Quantification of d-glucose using this approach was applied to banana samples over a period of 10 days. The results showed that the d-glucose levels in bananas increased as the fruits ripened, as expected. This work demonstrated a new and interesting approach for easy and efficient detection of analytes in raw fruit samples.

    更新日期:2017-11-10
  • Development of a modified QuEChERS method for multi-class pesticide analysis in human hair by GC-MS and UPLC-MS/MS
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Edouard Lehmann, Christelle Oltramare, Luiz Felippe de Alencastro

    The present study assessed the suitability of using QuEChERS procedure for the simultaneous determination and quantification of 37 multi-class pesticides in human hair. Matrix co-eluted material had a large influence on instrumental response sensitivity. Purification was needed although dSPE cleanup sorbent selection critically influenced analyte recovery. Optimized protocol using Z-Sep+sorbent successfully achieved recovery of 28 pesticides with high sensitivity, precision, and accuracy. Limits of detection ranged from 0.2 to 86.6 pg mg−1 and from 0.5 to 6.3 pg mg−1 for GC and UPLC amenable substances respectively. Pyrethroid pesticides were the most influenced by matrix effects which explained the higher limits of quantification retained for these substances. On the contrary, high sensitivity was achieved for UPLC amenable substances (LOD < 1 pg mg−1 for atrazine, deisopropylatrazine, desethylatrazine, and imidacloprid). Suitability for monitoring pesticide exposure was assessed by application of the proposed protocol to samples collected on the field. Hairs of the volunteers were found positive to 8 pesticides with every sample containing at least one residue. Among these pesticides, only 3 were reported as used in local vegetable production, which suggested other sources of exposure. The developed method offers a sensitive, robust, and accessible tool for biomonitoring of human exposure.

    更新日期:2017-11-10
  • An integrated method for simultaneously determining 10 classes of per- and polyfluoroalkyl substances in one drop of human serum
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Ke Gao, Jianjie Fu, Qiao Xue, Yili Li, Yong Liang, Yuanyuan Pan, Aiqian Zhang, Guibin Jiang

    Per- and polyfluoroalkyl substances (PFASs) represent a group of synthetic chemicals, and they have quite different physicochemical properties, which result in difficulties of their simultaneous determination in a single injection. A sensitive, reliable, and fully automated method was developed for simultaneously detecting 10 classes of PFASs (total of 43) in human serum using online Turboflow SPE-UHPLC-MS/MS. This method provided high linearity of matrix-matched calibration standards (R > 0.99), excellent method limits of detection (MLODs) (0.013–0.089 ng mL−1), satisfactory matrix spiked recoveries (84.3%–109%) and relative standard deviations (RSDs) (intra-day RSDs: 1.3%–12.6%, inter-day RSDs: 1.7%–13.8%, inter-week RSDs: 1.8–13.5%, inter-month RSDs: 3.1–12.4%), short analysis time (19 min per sample) and small sample amount requirement (25 μL), which were suitable for large-scale epidemiologic studies. Moreover, the method provided the feasibility of real-time monitoring for the degradation kinetics of PFASs precursors both in vitro and in vivo. The quality of the present method was further verified by repetitive analysis of a standard reference material (SRM 1957), with the deviations of the targeted PFAS concentrations ranging from 1.9% to 14.2% (n = 5) between the detected and reference values. The present study also determined values for several PFASs in SRM 1957 other than those on the certificate, for the first time, such as N-EtFOSA, 6:2 Cl-PFESA, and PFBA. Finally, the established method was applied to detect PFASs in serum samples of 15 ordinary people and 15 occupational workers, and 6:2 FTSA was found as the dominant precursor.

    更新日期:2017-11-10
  • A novel triplex isobaric termini labeling quantitative approach for simultaneously supplying three quantitative sources
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-09
    Hucong Jiang, Hongrui Yin, Liqi Xie, Ying Zhang, Lei Zhang, Peng-Yuan Yang, Haojie Lu

    Benefiting from high sensitivity and great ability to measure multiple samples simultaneously, isobaric tandem Mass spectrometry (MS2) quantification has been widely applied for protein biomarker screening. Here, a newly developed isobaric MS2 quantification method named triplex quantification by isobaric termini labeling (Triplex-QITL) was established. This method enables the accurate comparison of various fragment ions (reporter ions, amino acid fragments and N-/C-terminal fragments) based quantification to be operated in a single run. To our knowledge, this is the first time that this kind of comparison is achieved. In Triplex-QITL, proteins were first digested with Lys-C to produce peptides with lysine (K) at the C-termini, then dimethylation reagents and mTRAQ reagents were used to label the N-termini and C-termini of the peptides respectively. N- and C-terminal fragment ion pairs, reporter ions from mTRAQ (113,117,121) and a1 ion pairs were simultaneously generated in MS2 spectra. In simple sample experiment, not much difference in using various fragment ions for quantification was observed. When analyzing SW480 cell lysate, comparing with a1 ions, about two times of reproducible quantification results were achieved by reporter ions and N- and C-terminal ions. Meanwhile the measured quantification results were much closer to the expected results even in large ratios (1:10:10) using N- and C-terminal ions. Finally, Triplex-QITL was successfully applied to profile metastatic differences of three hepatocellular carcinoma (HCC) cell lines. In all, Triplex-QITL shows a promising future in quantitative proteomics.

    更新日期:2017-11-10
  • Rapid determination of immunosuppressive drug concentrations in whole blood by coated blade spray-tandem mass spectrometry (CBS-MS/MS)
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-08
    Germán Augusto Gómez-Ríos, Marcos Tascon, Nathaly Reyes-Garcés, Ezel Boyacı, Justen James Poole, Janusz Pawliszyn

    Coated Blade Spray (CBS) is a technology that efficiently integrates sample preparation and direct coupling to mass spectrometry (MS) on a single device. In this article, we present CBS-tandem mass spectrometry (CBS-MS/MS) as a novel tool for the rapid and simultaneous determination of four commonly used immunosuppressive drugs (ISDs) in whole blood: tacrolimus (TAC) and cyclosporine-A (CycA), which are calcineurin inhibitors; and sirolimus (SIR) and everolimus (EVR), which are both mTOR (mechanistic target of rapamycin) inhibitors. Given that CBS extracts via free concentration, analytes that are largely bound to plasma proteins or red blood cells provide considerably lower extraction recovery rates. Therefore, we defy the solventless philosophy of SPME-based techniques, like CBS, by performing the analyte-enrichment step via direct immersion in a solvent-modified matrix. The assay was linear within the evaluated range of concentrations (between 1 and 100 ng/mL for EVR/SIR/TAC and 10–1000 ng/mL for CycA), and the limits of quantification were determined to be 10 ng/mL for CycA and 1 ng/mL for EVR/SIR/TAC. Good accuracy (87–119%) and linearity (r2 ≥ 0.99) were attained over the evaluated range for all ISDs. Interassay imprecision (CV) determined from incurred sample reanalysis was ≤10% for all ISDs. Our method was validated using Liquichek™ whole blood immunosuppressant quality control (QC) standards purchased from Bio-Rad. Concentrations determined by CBS-MS/MS were inside the range specified by Bio-Rad and within 15% of the expected mean value for all ISDs at all QC levels. Furthermore, the effect of different hematocrit levels (20, 45, and 70%) in the entire calibration range was carefully studied. No statistical differences (RSD ≤ 7%) in the calibration curve slopes of ISDs in blood were observed. CBS offers a simpler workflow than that of traditional methods; it eliminates the need for chromatographic separation and provides a clean extract that allows for long-term MS instrumental operation with minimal maintenance. Additionally, because CBS integrates all analytical steps into one device, it eliminates the risk of instrumental carry-over and can be used as a low-cost disposable device for sample preparation and analysis. Fully-automated sample preparation simplifies the method and allows for total analysis times as short as 3 min with turn-around times of less than 90 min.

    更新日期:2017-11-10
  • Behavior and kinetic of hydrolysis of amine boranes in acid media employed in chemical vapor generation
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-03
    Lucia D'Ulivo, Roberto Spiniello, Massimo Onor, Beatrice Campanella, Zoltan Mester, Alessandro D'Ulivo
    更新日期:2017-11-03
  • Tutorial: Correction of shifts in single-stage LC-MS(/MS) data
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-02
    Vikram Mitra, Age Smilde, Rainer Bischoff, Péter Horvatovich
    更新日期:2017-11-03
  • Mass spectrometry based analytical approaches and pitfalls for toxicometabolomics of arsenic in mammals: A tutorial review
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-11-02
    T. García-Barrera, G. Rodríguez-Moro, B. Callejón-Leblic, A. Arias-Borrego, J.L. Gómez-Ariza
    更新日期:2017-11-03
  • 更新日期:2017-10-31
  • A simple and sensitive competitive bio-barcode immunoassay for triazophos based on multi-modified gold nanoparticles and fluorescent signal amplification
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-10-30
    Chan Zhang, Pengfei Du, Zejun Jiang, Maojun Jin, Ge Chen, Xiaolin Cao, Xueyan Cui, Yudan Zhang, Ruixing Li, A.M. Abd El-Aty, Jing Wang
    更新日期:2017-10-31
  • Chromatographic separation of the theranostic radionuclide 111Ag from a proton irradiated thorium matrix
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-10-30
    Tara Mastren, Valery Radchenko, Jonathan W. Engle, John W. Weidner, Allison Owens, Lance E. Wyant, Roy Copping, Mark Brugh, F. Meiring Nortier, Eva R. Birnbaum, Kevin D. John, Michael E. Fassbender
    更新日期:2017-10-30
  • Hydrogel-based suspension array for biomarker detection using horseradish peroxidase -mediated silver precipitation
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-10-30
    Dina Shohatee, Joshua Keifer, Nicholas Schimmel, Swetaparna Mohanty, Gargi Ghosh
    更新日期:2017-10-30
  • Thread based electrofluidic platform for direct metabolite analysis in complex samples
    Anal. Chim. Acta (IF 4.95) Pub Date : 2017-10-28
    Joan M. Cabot, Michael C. Breadmore, Brett Paull
    更新日期:2017-10-28
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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