• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-21
Rodrigo R. de Oliveira, Claudio Avila, Richard Bourne, Frans Muller, Anna de Juan

Abstract Process analytical technologies (PAT) applied to process monitoring and control generally provide multiple outputs that can come from different sensors or from different model outputs generated from a single multivariate sensor. This paper provides a contribution to current data fusion strategies for the combination of sensor and/or model outputs in the development of multivariate statistical process control (MSPC) models. Data fusion is explored through three real process examples combining output from multivariate models coming from the same sensor uniquely (in the near-infrared (NIR)-based end point detection of a two-stage polyester production process) or the combination of these outputs with other process variable sensors (using NIR-based model outputs and temperature values in the end point detection of a fluidized bed drying process and in the on-line control of a distillation process). The three examples studied show clearly the flexibility in the choice of model outputs (e.g. key properties prediction by multivariate calibration, process profiles issued from a multivariate resolution method) and the benefit of using MSPC models based on fused information including model outputs towards those based on raw single sensor outputs for both process control and diagnostic and interpretation of abnormal process situations. The data fusion strategy proposed is of general applicability for any analytical or bioanalytical process that produces several sensor and/or model outputs. Graphical abstract

更新日期：2020-01-21
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-20
Payam Hashemi, Petra Mischnick

Abstract Multi-block glucans comprising permethylated and partially methylated blocks are compounds of interest. In order to monitor their formation by transglycosylation of corresponding starting glucans, a method has been developed and applied to model compounds. This method allows determining the average length of the blocks and the progress of incorporation of methyl blocks in partially methylated sequences with a random distribution. The method, comprising liquid chromatography mass spectrometry (LC-MS) and electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MSn) measurements of two types of peralkylated glucans representing derivatives of the target compounds, is comprehensively described and discussed. ESI-MSn allows looking into the sequences of oligomeric domains. In addition, transglycosylation is followed by attenuated total reflection FTIR and NMR spectroscopy. Graphical abstract

更新日期：2020-01-21
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-18
Fan Pu, Sangeeta Pandey, Lane R. Bushman, Peter L. Anderson, Zheng Ouyang, R. Graham Cooks

Unfortunately, after online publication, a formatting mistake was found in Table 1 (Chemical structures and MRM transitions used for quantitation). The original article has been corrected.

更新日期：2020-01-21
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-18
Hyo-Jin Kim, Yoo-Jin Lee, Seungyeon Lee, You-Rim Lee, Hyunsong Son, Miji Shin, Hyebin Choi, Jaehee Yu, Jiyeong Lee, Hee-Gyoo Kang

Abstract Bloodstains found at crime scenes contain immense information about the crime; thus, studies involving analysis of small molecules in bloodstains have been conducted. However, most of these studies have not accounted for the difference in the results of small molecule analysis due to the surface of bloodstains. To evaluate the “surface effect,” we prepared bloodstains on seven surfaces, including both absorbent and non-absorbent surfaces, and performed global small molecule analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). We used three indicators: (1) count recovery rate (%) of molecular features (MFs), (2) the number of MFs extracted from the surface without bloodstains, and (3) difference in abundance recovery rate (%) of MFs, to determine the ranking of the seven surfaces in the order of their similarity with blood. We also confirmed the correlation between each surface and blood through multivariate analysis. We found that the non-absorbent surfaces ranked better than the absorbent surfaces; wooden flooring was ranked as the most efficient surface, followed by stainless, vinyl flooring, glass, tile, filter paper, and mixed cotton. This study will help in the selection of the most efficient surface for collection of bloodstains for small molecule analysis from a crime scene. This is the first study to identify the effects of surface on extraction of global small molecules from bloodstains; it will help forensic scientists in obtaining more accurate information from small molecules present in the bloodstains collected at the field. Graphical abstract

更新日期：2020-01-21
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-17
Ruth Rodríguez-Ramos, Bárbara Socas-Rodríguez, Álvaro Santana-Mayor, Miguel Ángel Rodríguez-Delgado

Abstract In this work, the development of a simple, fast and reliable method for the evaluation of a group of twelve plastic migrants in alcoholic and non-alcoholic beverages widely consumed by the population has been carried out. For that, a modified QuEChERS method for the extraction and preconcentration of the target compounds has been used prior to their separation and quantification by gas chromatography coupled to triple quadrupole tandem mass spectrometry. The whole methodology was validated for beer, cider and grape juice matrices, using dibutyl phthalate-3,4,5,6-d4 as surrogate. Recovery ranged from 75 to 120% for all matrices with relative standard deviation values lower than 20%, and the limits of quantification of the method were achieved in the range 0.034–1.415 μg/L. Finally, the analysis of different beer, cider and grape juice samples commercialised in different supermarkets of Tenerife was carried out, finding the presence of four of the evaluated phthalates in the range 0.14–1.1 μg/L in some of the evaluated beers, six of them in several cider samples, in the range 0.3–2.1 μg/L, and one in the range 1.2–1.5 μg/L in three of the analysed grape juices.

更新日期：2020-01-21
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-17
Minye Yang, Meihui Cui, Weixun Wang, Yaodong Yang, Jin Chang, Jianye Hao, Hanjie Wang

Abstract Methods for detecting mycotoxins are very important because of the great health hazards of mycotoxins. However, there is a high background and low signal-to-noise ratio in real-time sensing, and therefore it is difficult to meet the fast, accurate, and convenient requirements for control of food quality. Here we constructed a quantitative fluorescence image analysis based on multicolor upconversion nanocrystal (UCN)-encoded microspheres for detection of ochratoxin A and zearalenone. The background-free encoding image signal of UCN-doped microspheres was captured by fluorescence microscopy under near-infrared excitation, whereas the detection image signal of phycoerythrin-labeled secondary antibodies conjugated to the microspheres was captured under blue light excitation. We custom-wrote an algorithm to analyze the two images for the same sample in 10 s, and only the gray value in the red channel of the secondary probe confirmed the quantity. The results showed that this novel detection platform performed feasible and reliable fluorescence image measurements by this method. Additionally, the limit of detection of was 0.34721 ng/mL for ochratoxin A and 0.41162 ng/mL for zearalenone. We envision that this UCN encoding strategy will be usefully applied for fast, accurate, and convenient testing of multiple food contaminants to ensure the safety of the food.

更新日期：2020-01-17
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-17
Fernanda Bertuccez Cordeiro, Alan K. Jarmusch, Marisol León, Christina Ramires Ferreira, Valentina Pirro, Livia S. Eberlin, Judy Hallett, Maria Angelica Miglino, Robert Graham Cooks

Abstract Merging optical images of tissue sections with the spatial distributions of molecules seen by imaging mass spectrometry is a powerful approach to better understand the metabolic roles of the mapped molecules. Here, we use histologically friendly desorption electrospray ionization–mass spectrometry (DESI-MS) to map the lipid distribution in tissue sections of ovaries from cows (N = 8), sows (N = 3), and mice (N = 12). Morphologically friendly DESI-MS imaging allows the same sections to be examined for morphological information. Independent of the species, ovarian follicles, corpora lutea, and stroma could be differentiated by principal component analysis, showing that lipid profiles are well conserved among species. As examples of specific findings, arachidonic acid and the phosphatidylinositol PI(38:4), were both found concentrated in the follicles and corpora lutea, structures that promoted ovulation and implantation, respectively. Adrenic acid was spatially located in the corpora lutea, suggesting the importance of this fatty acid in the ovary luteal phase. In summary, lipid information captured by DESI-MS imaging could be related to ovarian structures and data were all conserved among cows, sows, and mice. Further application of DESI-MS imaging to either physiological or pathophysiological models of reproductive conditions will likely expand knowledge of the roles of specific lipids and pathways in ovarian activity and mammalian fertility. Graphical abstract Desorption electrospray ionization–mass spectrometry (DESI-MS) is performed directly from frozen ovarian tissue sections placed onto glass slides. Because the desorption and ionization process of small molecules is so gentle, the tissue architecture is preserved. The sample can then be stained and tissue morphology information can be overlaid with the chemical information obtained by DESI-MS.

更新日期：2020-01-17
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-16
Marla R. Bianca, Daniel R. Baluha, Michael Gonsior, Philippe Schmitt-Kopplin, Rossana Del Vecchio, Neil V. Blough

Abstract A prior method of mass labeling ketone-/aldehyde-containing species in natural dissolved organic matter (DOM) is further developed and applied. This application involved the treatment of Suwannee River fulvic acid (SRFA) with increasing concentrations of sodium borodeuteride (NaBD4), followed by detection of reduced species via negative mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS). The extent of reduction, as determined by ESI FTICR MS, resulting from increasing concentrations of NaBD4 correlated well with changes in the absorption and emission spectra of the corresponding untreated and borodeuteride-reduced samples, providing evidence that ketone/aldehyde functional groups contribute substantially to the bulk optical properties of SRFA. Furthermore, the differences in the reactivity and abundance of ketone-/aldehyde-containing species for various regions in Van Krevelen plots were revealed, thus showing how this mass labeling method can be used to provide more detailed structural information about components within complex DOM samples than that provided by the determination and analysis of molecular formulae alone. Graphical abstract

更新日期：2020-01-17
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-16
Verena K. Meyer, Claire V. Chatelle, Wilfried Weber, Reinhard Niessner, Michael Seidel

For the first time, a flow-based regenerable chemiluminescence receptor assay is established that is eminently suited as screening method for the detection of widely used tetracyclines (TCs) in environmental and food samples. The complex functionality and high reactivity of TCs complicate the creation of immunogens which is currently the bottleneck for developing sensitive immunoassays. In this case, competitive bioreceptor assays for the analysis of small organic molecules are preferable and, moreover, flow-based regenerable bioassays are optimally suited for automated analysis applications. Therefore, the solution for rapid and sensitive analysis of TCs is the regenerable CL receptor assay with a covalently immobilized DNA oligonucleotide containing the specific operator sequence tetO to which the repressor protein TetR binds only in the absence of TCs. The TC measurements are performed on the CL microarray analysis platform MCR 3 within 30 min per sample. The LoD in spiked tap water was determined to be 0.1 μg L−1, and for 1 μg L−1 TET, recoveries of 77% ± 16% were obtained. Due to the stability of the immobilized DNA oligonucleotide and the resulting regenerability of the assay for various measurements, the new method is highly cost- and resource-efficient and ideally suited for the monitoring of environmental samples in the field.

更新日期：2020-01-17
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-16
Avik. J. Ghoshdastidar, Janani Ramamurthy, Maxwell Morissette, Parisa A. Ariya

The authors would like to call the reader’s attention to the fact that, unfortunately, there was an unintentional oversight regarding the funding information in this manuscript; please find the correct information below.

更新日期：2020-01-16
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-16
Van Liem-Nguyen, Hoang-Tung Nguyen-Ngoc, Gbotemi A. Adediran, Erik Björn

Methylmercury (MeHg) is one of the most potent neurotoxins. It is produced in nature through the methylation of inorganic divalent mercury (HgII) by phylogenetically diverse anaerobic microbes. The mechanistic understanding of the processes that govern the extent of bacterial export of MeHg, its bioaccumulation, and bio-toxicity depends on accurate quantification of its species, especially its complexation with low molecular mass thiols; organometallic complexes that are difficult to detect and measure in natural conditions. Here, we report the development of a novel analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 13 MeHg complexes with important thiol compounds which have been observed in the environment and in biological systems. By using online preconcentration via solid phase extraction (SPE), the method offers picomolar (12–530 pM) detection limits, the lowest reported so far for the determination of MeHg compounds. Among three different SPE materials, a weak cation exchange phase showed the best efficiency at a low pH of 2.5. We further report the presence of MeHg-cysteine, MeHg-cysteamine, MeHg-penicillamine, MeHg-cysteinylglycine, and MeHg-glutamylcysteine as the predominant MeHg–thiol complexes in the extracellular milieu of an important HgII methylating bacterium, Geobacter sulfurreducens PCA, exposed to 100 nM of HgII.

更新日期：2020-01-16
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-16
Bastian Schulze, Tobias Bader, Wolfram Seitz, Rudi Winzenbacher

Abstract To close the “analytical gap” in the liquid chromatographic (LC) analysis of highly polar substances, two techniques which have been suggested earlier were tested in terms of retention factors and detection limits: hydrophilic interaction liquid chromatography (HILIC) and mixed-mode chromatography (MMC). A substance mix of 55 analytes ranging from logD − 8.2 to 3.4 and 17 different LC columns, also comprising additional reversed-phase columns were used. Contrary to most reversed-phase columns, column bleed has been identified as an important factor, which may cause serious restrictions during high-resolution mass spectrometric detection (HRMS). We found that highly abundant background masses continuously eluting from the columns heavily influence ion transmission to the detector. As a result, the linear dynamic range as well as the sensitivity decreases and thus limits the HRMS applicability of some columns. We therefore recommend a thorough investigation of ion transmission during HRMS method development. This will help to maintain the high potential of HRMS in terms of qualitative and quantitative screening analysis.

更新日期：2020-01-16
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-15
Tianyang Wang, Song Lin, Ran Liu, Hua Li, Zihan Liu, Xinnong Zhang, Huarong Xu, Qing Li, Kaishun Bi

Abstract Acute lung injury (ALI) is a clinically common and serious disease, underscoring the urgent need for clarification of its pathogenesis. According to traditional Chinese medicine (TCM) theories on the “lung–spleen–intestine axis” and its correlation with ALI, a high-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (HPLC–QTOF-MS) metabolomic platform was applied to identify biomarkers from five bio-samples of control and model rats challenged with intratracheally administered lipopolysaccharide (LPS) based on multivariate mathematical statistical analysis. As a result, 19, 24, 24, 15 and 29 altered metabolites were identified in serum, lung, bronchoalveolar lavage fluid (BALF), spleen and feces samples, respectively. Metabolic pathway analysis showed that linoleic acid, sphingolipid, glycerophospholipid and bile acid metabolism pathways were mainly altered by ALI. Additionally, ROC curves were applied to assess the specificity and sensitivity of the biomarkers. ALI characteristic metabolomic spectra were then established to differentiate the control from the model group with a similarity discriminative threshold of 0.7. Additionally, to compare the metabolomic profiles of the five bio-samples and establish metabolic similarities and differences among them, correlation analysis was conducted in order to delineate an objective law of endogenous linkage along the lung–spleen–intestine axis. Therefore, this study provides insights into the mechanisms involved in ALI from a metabolomics perspective, which can be applied in characterization of the mechanism and early disease detection. Graphical abstract

更新日期：2020-01-15
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-15
Bernhard Drotleff, Simon R. Roth, Kerstin Henkel, Carlos Calderón, Jörg Schlotterbeck, Merja A. Neukamm, Michael Lämmerhofer

Dental plaque is a structurally organized biofilm which consists of diverse microbial colonies and extracellular matrix. Its composition may change when pathogenic microorganisms become dominating. Therefore, dental biofilm or plaque has been frequently investigated in the context of oral health and disease. Furthermore, its potential as an alternative matrix for analytical purposes has also been recognized in other disciplines like archeology, food sciences, and forensics. Thus, a careful in-depth characterization of dental plaque is worthwhile. Most of the conducted studies focused on the screening of microbial populations in dental plaque. Their lipid membranes, on the other hand, may significantly impact substance (metabolite) exchange within microbial colonies as well as xenobiotics uptake and incorporation into teeth. Under this umbrella, a comprehensive lipidomic profiling for determination of lipid compositions of in vivo dental plaque samples and of in vitro cultivated biofilm as surrogate matrix to be used for analytical purposes has been performed in this work. An untargeted lipidomics workflow utilizing a ultra-high-performance liquid chromatography (UHPLC)-quadrupole-time-of-flight (QTOF) platform together with comprehensive SWATH (sequential window acquisition of all theoretical fragment ion mass spectra) acquisition and compatible software (MS-DIAL) that comprises a vast lipid library has been adopted to establish an extensive lipidomic fingerprint of dental plaque. The main lipid components in dental plaque were identified as triacylglycerols, followed by cholesterol, cholesteryl esters as well as diacylglycerols, and various phospholipid classes. In vivo plaque is a rare matrix which is usually available in very low amounts. When higher quantities for specific research assays are required, efficient ways to produce an appropriate surrogate matrix are mandatory. A potential surrogate matrix substituting dental plaque was prepared by cultivation of in vitro biofilm from saliva and similarities and differences in the lipidomics profile to in vivo plaque were mapped by statistical evaluation post-analysis. It was discovered that most lipid classes were highly elevated in the in vitro biofilm samples, in particular diacylglycerols, phosphatidylglycerols, and phosphatidylethanolamines (PEs). Furthermore, an overall shift from even-chain lipid species to odd-chain lipids was observed in the cultivated biofilms. On the other hand, even-chain phosphatidylcholines (PCs), lysoPCs, cholesteryl esters, and cholesterol-sulfate were shown to be specifically increased in plaque samples.

更新日期：2020-01-15
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-15
Thao Nhi Le, David da Silva, Cyril Colas, Eric Darrouzet, Patrick Baril, Lucie Leseurre, Benoît Maunit

Insect venom is a highly complex mixture of bioactive compounds, containing proteins, peptides, and small molecules. Environmental factors can alter the venom composition and lead to intraspecific variation in its bioactivity properties. The investigation of discriminating compounds caused by variation impacts can be a key to manage sampling and explore the bioactive compounds. The present study reports the development of a peptidomic methodology based on UHPLC–ESI-QTOF–HRMS analysis followed by a nontargeted multivariate analysis to reveal the profile variance of Vespa velutina venom collected in different conditions. The reliability of the approach was enhanced by optimizing certain XCMS data processing parameters and determining the sample peak threshold to eliminate the interfering features. This approach demonstrated a good repeatability and a criterion coefficient of variation (CV) > 30% was set for deleting nonrepeatable features from the matrix. The methodology was then applied to investigate the impact of collection period variation. PCA and PLS-DA models were used and validated by cross-validation and permutation tests. A slight discrimination was found between winter and summer hornet venom in two successive years with 10 common discriminating compounds.

更新日期：2020-01-15
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-14
Farhad Shiri, Kevin E. Petersen, Valentin Romanov, Qin Zou, Bruce K. Gale

Abstract Virus-like particles (VLPs) are widely used in medicine, but can be difficult to characterize and isolate from aggregates. In this research, primarily cyclical electrical field–flow fractionation (CyElFFF) coupled with multi-angle light scattering (MALS), and dynamic light scattering (DLS) detectors, was used for the first time to perform size and electrical characterization of three different types of Q beta bacteriophage virus-like particles (VLPs): a blank Q beta bacteriophage which is denoted as VLP and two conjugated ones with different peptides. The CyElFFF results were verified with transmission electron microscopy (TEM). Asymmetrical flow field–flow fractionation (AF4) coupled with MALS was also applied using conditions similar to those used in the CyElFFF experiments, and the results of the two techniques were compared to each other. Using these techniques, the size and electrophoretic characteristics of the fractionated VLPs in CyElFFF were obtained. The results indicate that CyElFFF can be used to obtain a clear distribution of electrophoretic mobilities for each type of VLP. Accordingly, CyElFFF was able to differentially retain and isolate VLPs with high surface electric charge/electrophoretic mobility from the ones with low electric charge/electrophoretic mobility. Regarding the size characterization, the size distribution of the eluted VLPs was obtained using both techniques. CyElFFF was able to identify subpopulations that did not appear in the AF4 results by generating a shoulder peak, whereas AF4 produced a single peak. Different size characteristics of the VLPs appearing in the shoulder peak and the main peak indicate that CyElFFF was able to isolate aggregated VLPs from the monomers partially. Graphical abstract

更新日期：2020-01-14
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-13
Wenshuai Li, Saipeng Huang, Huiyun Wen, Yane Luo, Jiewei Cheng, Zhao Jia, Pu Han, Weiming Xue

The nitrite ion (NO2−) is a vital inorganic species that occurs both in natural ecological systems and human bodies. The high concentration of NO2− can be harmful for animal and human health. It is important to develop a simple, sensitive, reliable, and economic methodology to precisely monitor NO2− in various environmental and biological fields. Thus, a novel nitrite biosensor based on carbon quantum dots (PA-CDs) has been constructed and prepared via a high-efficiency, one-pot hydrothermal route using primary arylamines (PA) such as m-phenylenediamine. The device exhibits bright green fluorescence and a high quantum yield of 20.1% in water. In addition, the PA-CDs also possess two broad linear ranges: 0.05–1.0 μM and 1.0–50 μM with a low detection limit of 7.1 nM. The classical diazo reaction is firstly integrated into the PA-CD system by primary arylamines, which endows the system with high sensitivity and specific selectivity towards nitrite. Importantly, the nanosensor can detect NO2− in environmental water and serum samples with high fluorescence recoveries, demonstrating its feasibility in practical applications. This work broadens a new method to fabricate novel nanosensors and provides a prospective application for fluorescent carbon quantum dots (CDs).

更新日期：2020-01-13
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-13
Kamlesh Shrivas, Monisha, Tushar Kant, Indrapal Karbhal, Ramsingh Kurrey, Bhuneshwari Sahu, Deepak Sinha, Goutam Kumar Patra, Manas Kanti Deb, Shamsh Pervez

We report a smartphone–paper-based sensor impregnated with cetyltrimethylammonium bromide modified silver nanoparticles (AgNPs/CTAB) for determination of Fe3+ in water and blood plasma samples. The methodology for determination of Fe3+ is based on the change in signal intensity of AgNPs/CTAB fabricated on a paper substrate after the deposition of analyte, using a smartphone followed by processing with ImageJ software. The mechanism of sensing for detection and determination of Fe3+ is based on the discoloration of AgNPs which impregnated the paper substrate. The discoloration is attributed to the electron transfer reaction taking place on the surface of NPs in the presence of CTAB. Fe3+ was determined when the paper was impregnated with 1 mM AgNPs for 5 min of reaction time and the substrate was kept under acidic conditions. The linear range for determination of total iron in terms of Fe3+ was 50–900 μg L−1 with a limit of determination (LOD) of 20 μg L−1 and coefficient of variation (CV) of 3.2%. The good relative recovery of 91.3–95.0% and interference studies showed the selectivity of the method for determination of total iron in water and blood plasma samples. Smartphone–paper-based sensors have advantages of simplicity, rapidity, user-friendliness, low cost, and miniaturization of the method for on-site determination of total iron compared to methods that require sophisticated analytical instruments.

更新日期：2020-01-13
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-11
Sabrina Geisslitz, Antoine H. P. America, Katharina Anne Scherf

High-molecular-weight glutenin subunits (HMW-GS) play an important role for the baking quality of wheat. The ancient wheats emmer and spelt differ in their HMW-GS pattern compared to modern common wheat and this might be one reason for their comparatively poor baking quality. The aim of this study was to elucidate similarities and differences in the amino acid sequences of two 1Bx HMW-GS of common wheat, spelt and emmer. First, the sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE) system was optimized to separate common wheat, spelt and emmer Bx6 and Bx7 from other HMW-GS (e.g., 1Ax and 1By) in high concentrations. The in-gel digests of the Bx6 and Bx7 bands were analyzed by untargeted LC-MS/MS experiments revealing different UniProtKB accessions in spelt and emmer compared to common wheat. The HMW-GS Bx6 and Bx7, respectively, of emmer and spelt showed differences in the amino acid sequences compared to those of common wheat. The identities of the peptide variations were confirmed by targeted LC-MS/MS. These peptides can be used to differentiate between Bx6 and Bx7 of spelt and emmer and Bx6 and Bx7 of common wheat. The findings should help to increase the reliability and curation status of wheat protein databases and to understand the effects of protein structure on the functional properties.

更新日期：2020-01-13
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-11
Zélie Triaux, Hugues Petitjean, Eric Marchioni, Maria Boltoeva, Christophe Marcic

Deep eutectic solvents (DESs) were investigated as extracting solvent for headspace single-drop microextraction (HS-SDME). The extraction efficiency of 10 DESs mainly composed of tetrabutylammonium bromide (N4444Br) and long-chain alcohols was evaluated for the extraction of terpenes from six spices (cinnamon, cumin, fennel, clove, thyme, and nutmeg). The DES composed of N4444Br and dodecanol at a molar ratio of 1:2 showed the highest extraction efficiency and was selected to conduct the extractions of terpenes in the rest of the study. HS-SDME was optimized by design of experiments. Only two parameters from the four studied showed a significant influence on the efficiency of the method: the extraction time and the extraction temperature. The optimal extraction conditions were determined by response surface methodology. All extracts were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). More than 40 terpenes were extracted and identified in nutmeg, the richest extract in terpenes in this study. Quantitative analysis based on 29 standards was conducted for each extract. Good linearity was obtained for all standards (R2 > 0.99) in the interval of 1 to 500 μg/g. Limits of quantification ranged from 0.47 μg/g (borneol) to 86.40 μg/g (α-farnesene) with more than half of the values under 2 μg/g. HS-SDME is simple, rapid, and cheap compared with conventional extraction methods. The use of DESs makes this extraction method “greener” and it was shown that DESs can be suitable solvents for the extraction of bioactive compounds from plants.

更新日期：2020-01-13
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-11
Qingqing Tan, Ruirui Zhang, Guoyan Zhang, Xiaoya Liu, Fengli Qu, Limin Lu

Abstract Herein, a dual-emission metal-organic framework based ratiometric fluorescence nanoprobe was reported for detecting copper(II) ions. In particular, carbon dots (CDs) and gold nanoclusters (AuNCs) were embedded into ZIF-8 (one of the classical metal-organic frameworks) to form CDs/AuNCs@ZIF-8 nanocomposites, which exhibited dual-emission peaks at UV excitation. In the presence of Cu2+, the fluorescence attributed to AuNCs can be rapidly quenched, while the fluorescence of CDs serves as reference with undetectable changes. Therefore, the CDs/AuNCs@ZIF-8 nanocomposites were utilized as a ratiometric fluorescence nanoprobe for sensitive and selective detection of Cu2+. A good linear relationship between the ratiometric fluorescence signal of CDs/AuNCs@ZIF-8 and Cu2+ concentration was obtained in the range of 10−3–103 μM, and the detection limit was as low as 0.3324 nM. The current ratiometric fluorescence nanoprobe showed promising prospects in cost-effective and rapid determination of Cu2+ ions with good sensitivity and selectivity. Furthermore, this nanoprobe has been successfully applied for the quantitative detection of Cu2+ in serum samples, indicating its value of practical application. Graphical abstract Carbon dots (CDs) and gold nanoclusters (AuNCs) were embedded into metal-organic frameworks (ZIF-8) to form CDs/AuNCs@ZIF-8 nanocomposites, which exhibited dual-emission peaks at 365 nm excitation. In the presence of Cu2+, the fluorescence emission peak at 574 nm can rapidly respond by quenching, while the fluorescence at 462 nm serves as reference with undetectable changes.

更新日期：2020-01-13
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-10
Tianjiao Zhang, Haijian Zhao, Miao Li, Jie Zeng, Jing Wang, Qichen Long, Yufei Wang, Chuanbao Zhang, Wenxiang Chen

Accurate and precise cortisol measurements are requisite for ensuring appropriate diagnosis and management of diseases related with adrenal or pituitary gland disorders. Prompted by the needs in characterization of certified reference materials and quality assurance for serum cortisol measurements, we developed and evaluated a highly reliable measurement procedure based on isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) combined with dextran sulfate-Mg2+ precipitation as the sample pretreatment. An appropriate amount of serum was accurately weighed and spiked with the isotope labelled internal standard. After precipitation, massive lipids and lipoproteins were removed from serum matrix. The clear supernatant was transferred and extracted with ethyl acetate-hexane solution. The cortisol was analyzed with LC-MS/MS in positive electrospray ionization mode. The within-run and total coefficient of variations (CVs) ranged from 0.3 to 0.6% and 0.7 to 1.2%, respectively, for a concentration range of 76.30 to 768.04 nmol/L. A regression comparison of the results obtained by the present method and the certified values of ERM-DA451 showed agreement with no statistical difference (Y = 1.0092 X-0.7455; 95% CI for the slope, 0.9940 to 1.0212; 95% CI for the intercept, − 3.6575 to 2.6390, r2 = 0.999). All structural analogs of cortisol tested were well resolved from cortisol in 12 min on a phenyl ligand column under an isocratic elution. The limit of quantification was estimated to 5 pg cortisol in absolute amount. This method is accurate and simple and can be served as a candidate reference measurement procedure in establishment of serum cortisol reference system.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-10
Karina Aguilar-Arteaga, Cynthia Hernández-Mera, Luis Díaz-Batalla, Araceli Castañeda-Ovando, Alida Elizabeth Cruz-Pérez, Enrique Barrado-Esteban, Manuel Carrillo-Cárdenas

Abstract The combination of two microextraction techniques (dispersive liquid-liquid microextraction [DLLME] and magnetic dispersive microsolid phase extraction [MDMSPE]) was developed and reported for atrazine and simazine preconcentration from wastewater samples. The proposal methodology involved the use of magnetite supports functionalized with different alkyl or phenyl groups. The magnetic adsorbents were synthesized by the solvothermal method assisted by microwave, characterized, and used in the sample preconcentration of atrazine and simazine. The method validation included parameters such as the wastewater matrix effect, repeatability, and recovery. The analyte separation and quantification were performed by high-performance liquid chromatography with ultraviolet detection (HPLC-DAD). Parameters, such as the polarity and mass of magnetic solids and pH, were evaluated to provide better extraction performance. The highest recoveries (> 95%) were obtained with 50 mg of the phenyl group support (CS2) at pH 5, using 5 mL of the sample and carbon tetrachloride and methanol, as extraction and dispersive solvents, respectively. The lowest limits of detection (LOD) achieved were 13.16 and 13.86 ng L−1, and the limits of quantification (LOQ) were 43.89 and 46.19 ng L−1 for simazine and atrazine, respectively, with repeatability (expressed as %RSD) below 5% in all cases. The developed method is simple, easy, and low cost for the analysis of two herbicides potentially dangerous for environmental and human health. Graphical abstract

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-10
Bo Zhao, Jingjing Gao, Mahalia A. C. Serrano, Kathleen F. Arcaro, S. Thayumanavan, Richard W. Vachet

Abstract Human breast milk is an understudied biological fluid that may be useful for early detection of breast cancer. Methods for enriching and detecting biomarkers in human breast milk, however, are not as well-developed as compared with other biological fluids. In this work, we demonstrate a new enrichment method based on polymeric nanoassemblies that is capable of enhancing the mass spectrometry–based detection of peptides and proteins in human breast milk. In this method, positively charged nanoassemblies are used to selectively deplete abundant proteins in milk based on electrostatic interactions, which simplifies the mixture and enhances detection of positively charged peptides and proteins. Negatively charged nanoassemblies are used in a subsequent enrichment step to further enhance the detection and quantification of trace-level peptides and proteins. Together the depletion and enrichment steps allow model biomarkers to be detected at low nM levels, which are close to instrumental limits of detection. This new method not only demonstrates the ability to detect proteins in human breast milk but also provides an alternative approach for targeted protein detection in complex biological matrices. Graphical abstract

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-10
Frank Wackenhut, Lukas A. Jakob, Otto Hauler, Alexander Stuhl, Florian Laible, Monika Fleischer, Kai Braun, Alfred J. Meixner

Abstract Using the localized surface plasmon resonance (LSPR) of gold nanoparticles for sensing applications has attracted considerable interest, since it can be very sensitive, even down to a single molecule, and selective for a specific analyte molecule with a suitable surface modification. LSPR sensing is usually based on the wavelength shift of the LSPR or a Fano resonance. Here, we present a new experimental approach based on the phase of the light scattered by a single gold nanoparticle by equipping a confocal microscope with an additional interferometer arm similar to a Michelson interferometer. The detected phase depends on the shape of the nanoparticle and the refractive index of the surrounding medium and can even be detected for off-resonant excitation. This can be used as a new and sensitive detection method in LSPR sensing, allowing the detection of changes to the local refractive index or the binding of molecules to the nanoparticle surface.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-10
Tatiana S. Svalova, Margarita V. Medvedeva, Anna A. Saigushkina, Ivan V. Kozitsin, Natalya N. Malysheva, Valeria O. Zhdanovskikh, A. V. Okhokhonin, Alisa N. Kozitsina

In this article, an original method is proposed for address and covalent immobilization of anti-E. coli antibodies on a screen-printed electrode (SPE). The method is based on a copper-catalyzed “click” reaction between a polyvinylbenzylazide (PVBA) film electrochemically deposited on the electrode surface and acetylene fragments of propargyl-N-hydroxysuccinimide ester. The products of electrochemical oxidation of copper particles incorporated in the polymer film on the electrode were first used for catalysis of the click reaction. This approach allowed us to reduce the immobilization time from a few hours for conventional methods to just 30 min, and to prevent denaturation of the immunoreceptor. The modified electrodes were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Based on the results obtained, a label-free impedimetric immunosensor for E. coli detection was developed. The detection limit of the immunosensor was estimated as 6.3 CFU/ml, with a linear range of 103–106 CFU/ml. The immunosensor demonstrated good stability during 30 days of storage in phosphate buffer solution (PBS, pH 7) and selectivity toward excess Staphylococcus aureus bacteria.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Thi Phuong Thuy Hoang, Morgane Barthélemy, Raphaël Lami, Didier Stien, Véronique Eparvier, David Touboul

In recent years, use of supercritical-fluid chromatography (SFC) with CO2 as the mobile phase has been expanding in the research laboratory and industry since it is considered to be a green analytical method. This technique offers numerous advantages, such as good separation and sensitive detection, short analysis times, and stability of analytes. In this study, a method for quantification of N-acyl homoserine lactones (AHLs), signaling molecules responsible for cell-to-cell communication initially discovered in bacteria, by SFC coupled with high-resolution mass spectrometry (HRMS) was developed. The SFC conditions and MS ionization settings were optimized to obtain the best separation and greatest sensitivity. The optimal analysis conditions allowed quantification of up to 30 AHLs in a single run within 16 min with excellent linearity (R2 > 0.998) and sensitivity (picogram level). This method was then applied to study AHL production by one Gram-negative endophytic bacterium, Paraburkholderia sp. BSNB-0670. Nineteen known AHLs were detected, and nine abundant HSLs were quantified. To further investigate the production of uncommon AHLs, a molecular networking approach was applied on the basis of the SFC–HRMS/MS data. This led to additional identification of four unknown AHLs annotated as N-3-hydroxydodecanoylol homoserine lactone, N-3-hydroxydodecadienoyl homoserine lactone, and N-3-oxododecenoyl homoserine lactones (two isomers).

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Supattra Muhammad-aree, Siriwan Teepoo

A field paper-based heavy metal strip was designed and implemented for simultaneous detection of the heavy metals Zn, Cr, Cu, Pb and Mn in wastewater samples. The colorimetric paper strip was fabricated by drop-casting of chromogenic reagents onto detection zones. When the fabricated paper strip was exposed to Zn, Cr, Cu, Pb and Mn, multiple colors appeared that were then recorded with a smartphone followed by processing in the Color Picker application. After optimizing the analytical parameters, such as the chromogenic concentration, pH and reaction time, the paper strip achieved detection limits of 0.63, 0.07, 0.17, 0.03 and 0.11 mg/L for Zn, Cr, Cu, Pb and Mn, respectively. Five heavy metals analyses were able to be performed within 1 min on one paper strip. This paper strip is accurate with recoveries from 87 to 107%. The results of the proposed paper strip correlated well with those determined by inductively coupled plasma-optical emission spectrometry of wastewater samples. The use of a single paper strip integrated with a smartphone for the detection of five heavy metals in wastewater represents an all-in-one device with on-site detection, leading to cost-effective and rapid assays that show a great application potential for on-site environmental monitoring.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Boris Bugsel, Christian Zwiener

The application of contaminated paper sludge on arable land in southwest Germany caused the occurrence of a broad range of poly- and perfluoroalkyl substances (PFASs) on soil. Recently, the dead-end transformation products (TPs) perfluorooctanoic acid and perfluorooctanesulfonic acid were detected in groundwater and drinking water. The precursors and other transformation products mostly remained unknown. Therefore, HRMS screening by Kendrick mass analysis and assignment of homologous series in combination with suspect screening were applied to identify original PFASs and their TPs in four different soil samples from sites where contaminated paper sludge was applied. In total, twelve compound classes comprising more than 61 PFASs could be fully or tentatively identified. The data reveal that contamination mainly originates from polyfluorinated dialkylated phosphate esters (from 4:2/6:2 to 12:2/14:2), N-ethyl perfluorooctane sulfonamide ethanol–based phosphate diesters (only C8/C8) and transformation products of these precursors. Contamination patterns can be attributed to PFASs used for paper impregnation and can vary slightly from site to site.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Panpan Dai, Chen Liu, Chenggen Xie, Jiajun Ke, Yong He, Liyun Wei, Lijuan Chen, Juncheng Jin

Abstract An enhanced cathodic electrochemiluminescence (ECL) assay for prostate-specific antigen (PSA) is developed based on the in situ activation of a semiconductor nanomaterial. An excellent ECL emitter (CdS/TiO2 nanotubes) was fabricated by the combination of TiO2 nanotubes (NTs) and thioglycolic acid-capped CdS nanocrystals (NCs). After the activation of the hydrogen peroxide-citric acid solution, the ECL signal was enhanced 265 times compared with that of the original TiO2 NT with H2O2 as co-reactant. For the ECL assay, activated CdS/TiO2 NTs were assembled with complementary DNA, PSA aptamer and probe DNA-functionalized SiO2@Pt nanoparticles (NPs) via DNA hybridization to form the detection platform. The SiO2@Pt NPs acted as ECL quencher of CdS/TiO2 NTs. In the presence of PSA, ECL increased after the release of pDNA-SiO2@Pt NPs because of the binding of PSA to the aptamer. An “off-on” ECL phenomenon appeared. The enhanced ECL signals were used for sensitive determination of PSA. The dynamic range was 0.001 to 50 ng mL−1 with a detection limit of 0.4 pg mL−1 (S/N = 3). This new approach conceivably paves the way for fabricating various other enhanced ECL emitter systems, with good application prospects in clinical practice. Graphical abstract The activated CdS/TiO2 nanotubes and SiO2@Pt nanoparticles were synthesized and used to develop an energy-transfer electrochemiluminescence analysis method with high sensitivity and anti-interference performance.

更新日期：2020-01-11
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Marie Fenclova, Milena Stranska-Zachariasova, Frantisek Benes, Alena Novakova, Petra Jonatova, Vladimir Kren, Libor Vitek, Jana Hajslova

Silymarin, milk thistle (Silybum marianum) extract, contains a mixture of mostly isomeric bioactive flavonoids and flavonolignans that are extensively studied, especially for their possible liver-protective and anticancer effects. Because of the differing bioactivities of individual isomeric compounds, characterization of their proportion in a mixture is highly important for predicting its effect on health. However, because of silymarin’s complexity, this is hardly feasible by common analytical techniques. In this work, ultraperformance liquid chromatography coupled with drift tube ion mobility spectrometry and quadrupole time-of-flight mass spectrometry was used. Eleven target silymarin compounds (taxifolin, isosilychristin, silychristins A and B, silydianin, silybins A and B, 2,3-cis-silybin B, isosilybins A and B and 2,3-dehydrosilybin) and five unknown flavonolignan isomers detected in the milk thistle extract were fully separated in a 14.5-min analysis run. All the compounds were characterized on the basis of their accurate mass, retention time, drift time, collision cross section and fragmentation spectra. The quantitative approach based on evaluation of the ion mobility data demonstrated lower detection limits, an extended linear range and total separation of interferences from the compounds of interest compared with the traditional approach based on evaluation of liquid chromatography–quadrupole time-of-flight mass spectrometry data. The following analysis of a batch of milk thistle-based food supplements revealed significant variability in the silymarin pattern, especially in the content of silychristin A and silybins A and B. This newly developed method might have high application potential, especially for the characterization of materials intended for bioactivity studies in which information on the exact silymarin composition plays a crucial role.

更新日期：2020-01-09
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-09
Enea Pagliano

Abstract Analytical chemists resort to derivatization for improving the detection performance of certain categories of analytes. Within this context, alkylation reactions are regarded as an important asset for many methods based on GC-MS and LC-MS. Trialkyloxonium tetrafluoroborates (R$$_{3}\textit {O}^{+}$$[BF4]−) are powerful alkylating agents with ionic liquid properties: they are nonvolatile salts soluble in water which are easier and safer to handle with respect to common alkylating agents like diazomethane. R$$_{3}\textit {O}^{+}$$[BF4]− can perform the alkylation in both organic and aqueous media at pH conditions ranging from acidic to alkaline. Recent analytical applications of trialkyloxonium derivatizations include the high-precision determination of inorganic anions in complex matrices, the qualitative confirmation of chemical warfare agent degradation products in soils, the profiling of carboxylic acids in urine, and the detection of protein post-translational modifications induced by carbon dioxide. The common denominator for all methods presented can be found in the simplicity of the alkylation protocol which, in most of the cases, requires a single step addition of the reagent directly to the sample. Graphical Abstract Alkylation with trialkyloxonium salts for GC-MS and LC-MS analysis

更新日期：2020-01-09
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-08
Xiaomin Yan, Wenjun Wang, Ziqiang Chen, Yu Xie, Qijuan Li, Ziwei Yu, Huiling Hu, Zhanguo Wang

更新日期：2020-01-08
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-08
Joshua Harrington Aheto, Xingyi Huang, Xiaoyu Tian, Yi Ren, Bonah Ernest, Evans Adingba Alenyorege, Chunxia Dai, Tu Hongyang, Zhang Xiaorui, Peichang Wang

Abstract The study assessed the feasibility of merging data acquired from hyperspectral imaging (HSI) and electronic nose (e-nose) to develop a robust method for the rapid prediction of intramuscular fat (IMF) and peroxide value (PV) of pork meat affected by temperature and NaCl treatments. Multivariate calibration models for prediction of IMF and PV using median spectra features (MSF) and image texture features (ITF) from HSI data and mean signal values (MSV) from e-nose signals were established based on support vector machine regression (SVMR). Optimum wavelengths highly related to IMF and PV were selected from the MSF and ITF. Next, recurring optimum wavelengths from the two feature groups were manually obtained and merged to constitute “combined attribute features” (CAF) which yielded acceptable results with (Rc2 = 0.877, 0.891; RMSEC = 2.410, 1.109; Rp2 = 0.790, 0.858; RMSEP = 3.611, 2.013) respectively for IMF and PV. MSV yielded relatively low results with (Rc2 = 0.783, 0.877; RMSEC = 4.591, 0.653; Rp2 = 0.704, 0.797; RMSEP = 3.991, 0.760) respectively for IMF and PV. Finally, data fusion of CAF and MSV was performed which yielded relatively improved prediction results with (Rc2 = 0.936, 0.955; RMSEC = 1.209, 0.997; Rp2 = 0.895, 0.901; RMSEP = 2.099, 1.008) respectively for IMF and PV. The results obtained demonstrate that it is feasible to mutually integrate spectral and image features with volatile information to quantitatively monitor IMF and PV in processed pork meat. Graphical abstract

更新日期：2020-01-08
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-08
Éder dos Santos Souza, Richard Perosa Fernandes, Wesley Nascimento Guedes, Fábio Neves dos Santos, Marcos Nogueira Eberlin, Norberto Peporine Lopes, Victor Damasceno Padovani, João Aristeu da Rosa

Abstract Triatominae are hematophagous insects involved in the transmission of Chagas disease. Among the 19 genera of the subfamily, those with the highest epidemiological importance regarding the dissemination of Trypanosoma cruzi are Panstrongylus, Rhodnius, and Triatoma. Of these three genera, Rhodnius presents the greatest difficulties for specific identification. Thus, there is a need to overcome the difficulties in identifying phenotypes of similar species of this genus. In the present study, the MALDI-TOF MS methodology was used to identify 12 Rhodnius species, among the 21 admitted. The MALDI-TOF MS methodology allowed specific characterization through the identification of peptides and proteins, starting from four different methods of extraction: (A) acetonitrile/formic acid (ACN/AF), (B) acetonitrile/trifluoroacetic acid (ACN/TFA), (C) isopropyl/formic acid (IPA/AF), and (D) methanol/formic acid (MeOH/AF), and four types of MALDI-TOF matrices: α-cyano-4-hydroxycinnamic acid (CHCA), sinapic acid (SA), 6-aza-2-thiothymine (ATT), and 2,6-dihydroxyacetophenone (DHAP). The experiments were performed by combining the four solvents and four matrices to select the best MALDI extraction/matrix. The application of the MALDI-TOF MS technique, through the digital mass spectrometry approach combined with chemometric tools, such as partial least squares-discriminant analysis (PLS-DA), was able to discriminate 12 species of Rhodnius genus, which are difficult to identify using morphological characteristics. Thus, in view of the results obtained, the methodology described in the present article can be applied with speed and efficiency for the discrimination of Triatominae species. Graphical Abstract

更新日期：2020-01-08
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-07
Anabel Villalonga, Ana María Pérez-Calabuig, Reynaldo Villalonga

Abstract During recent decades, nucleic acid aptamers have emerged as powerful biological recognition elements for electrochemical affinity biosensors. These bioreceptors emulate or improve on antibody-based biosensors because of their excellent characteristics as bioreceptors, including limitless selection capacity for a large variety of analytes, easy and cost-effective production, high stability and reproducibility, simple chemical modification, stable and oriented immobilization on electrode surfaces, enhanced target affinity and selectivity, and possibility to design them in target-sensitive 3D folded structures. This review provides an overview of the state of the art of electrochemical aptasensor technology, focusing on novel aptamer-based electroanalytical assay configurations and providing examples to illustrate the different possibilities. Future prospects for this technology are also discussed. Graphical abstract

更新日期：2020-01-07
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-07
Cemil Aydoğan

Abstract In the last decade, interest in food and plant natural products (FPNPs) has been growing due to their medical applications. Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) is the key to obtaining pure natural products for structure elucidation as well as for development into therapeutic agents. In this review, we will provide a summary of recent advances and applications related to the analysis of the most common FPNPs in studied matrices, in particular, polyphenols, peptides, carotenoids, alkaloids, terpenoids and glucosinolates by LC-HRMS. This paper also reviews the critical revision of this topic covering the works published in the last 4 years (early 2016–mid 2019). In addition, it gives an overview of the current state of various screening strategies (e.g. targeted, suspected, untargeted or retrospective) with discussion on future directions and perspectives of this technique. Graphical abstract

更新日期：2020-01-07
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-07
Mimi Shin, Daniel A. Friedman, Deborah M. Gordon, B. Jill Venton

Colonies of the red harvester ant, Pogonomyrmex barbatus, regulate foraging activity based on food availability and local conditions. Colony variation in foraging behavior is thought to be linked to biogenic amine signaling and metabolism. Measurements of differences in neurotransmitters have not been made among ant colonies in a natural environment. Here, for the first time, we quantified tissue content of 4 biogenic amines (dopamine, serotonin, octopamine, and tyramine) in single forager brains from 9 red harvester ant colonies collected in the field. Capillary electrophoresis coupled with fast-scan cyclic voltammetry (CE-FSCV) was used to separate and detect the amines in individual ant brains. Low levels of biogenic amines were detected using field-amplified sample stacking by preparing a single brain tissue sample in acetonitrile and perchloric acid. The method provides low detection limits: 1 nM for dopamine, 2 nM for serotonin, 5 nM for octopamine, and 4 nM for tyramine. Overall, the content of dopamine (47 ± 9 pg/brain) was highest, followed by octopamine (36 ± 10 pg/brain), serotonin (20 ± 4 pg/brain), and tyramine (14 ± 3 pg/brain). Relative standard deviations were high, but there was less variation within a colony than among colonies, so the neurotransmitter content of each colony might change with environmental conditions. This study demonstrates that CE-FSCV is a useful method for investigating natural variation in neurotransmitter content in single ant brains and could be useful for future studies correlating tissue content with colony behavior such as foraging.

更新日期：2020-01-07
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
Valentina Bello, Sabina Merlo

Abstract Spectral detection of light transmission through capillaries filled with a fluid sample is a powerful solution for evaluating its composition. In this work, we present an optical method to distinguish water and alcohol samples in a rectangular glass micro-capillary, coupled to an external fluidic path and laid flat onto an aluminum bulk mirror, from the spectral transmittance in the near-infra-red (NIR) wavelength range 1.15–1.65 μm, which becomes sample-specific thanks to the contribution given by the spectral absorption properties of the fluid. The readout beam of broadband radiation is shone on the upper flat side of the micro-capillary with an incidence angle of 14°, crosses the glass walls and the channel depth twice, since it is reflected by the mirror, and it is then coupled to the monochromator input of an optical spectrum analyzer. The theoretical transmission spectra of the capillary filled just with air as well as with distilled water, isopropanol, ethylene glycol, and 95% ethanol (with 5% water content) are derived using analytical equations including the wavelength-dependent attenuation due to fluid absorption. Experimental results relative to the wavelength dependence of the ratio between the spectral transmittance in the presence of the fluid sample and of just air are found to be in agreement with the calculated theoretical behavior. Grapical abstract

更新日期：2020-01-07
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
Jinshui Liu, Fangfei Wu, Ao Xie, Chenfu Liu, Huijuan Bao

Abstract Water-soluble nonconjugated fluorescent polymer nanoparticles (NFPNs) were prepared from branched polyethylenimine (PEI) and citric acid through an amide condensation reaction in the aqueous phase. The NFPNs were characterized using a transmission electron microscope, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectra (XPS). The NFPN fluorescence (with excitation/emission peaks at 360/450 nm) was quenched by 2,4,6-trinitrophenol (TNP) at trace concentrations through the inner filter effect and the formation of self-assembled non-fluorescent Meisenheimer complexes of TNP on the NFPN surfaces through acid–base interactions. The complexes effectively enriched TNP from the bulk solution on the NFPN surfaces through acid–base interactions, and the strong overlap between NFPN excitation and TNP absorption peaks contributed to NFPNs having good sensitivity and selectivity for TNP. The method was selective for TNP and was not sensitive to other interfering species. The calibration plot of log(F0/F) versus TNP concentration shows a linear relationship (R2 = 0.999) for TNP concentration in the range of 0.5–150 μM. The detection limit for TNP was 0.7 μM. The assay was successfully used to determine TNP in spiked lake water samples, and the recoveries were 96.6–102.7%.

更新日期：2020-01-06
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
Congmin Liu, Yudan Wang, Lei Zhang, Jia′an Qin, Xiaowen Dou, Yanwei Fu, Qian Li, Xue Zhao, Meihua Yang

We produced a prometryn-specific monoclonal antibody and propose a strategy for convenient on-site detection of prometryn residues in herbs for the first time. This strategy has perfect applicability in a complex herbal medicine matrix. The strategy combines a semiquantitative immunochromatographic strip assay with a heterologous indirect competitive ELISA. When there was no matrix interference, the ELISA had a half-maximal inhibitory concentration of 2.6 ng·mL-1 and a limit of detection of 0.2 ng·mL-1. The immunochromatographic strip assay can be completed within 5 min with a visual limit of detection of 1 ng·mL-1. Although the sample matrix had different effects on the sensitivity of the antibody, excellent repeatability and accuracy were achieved. The method was successfully applied for the screening and determination of prometryn residue in multiple complex herb samples for the first time, and the results were in good agreement with those obtained by liquid chromatography–tandem mass spectrometry. The proposed strategy is rapid, of high-throughput, and of low cost, and may be a promising choice for on-site detection of prometryn in different kinds of herbs.

更新日期：2020-01-06
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
M. Imran, Narendra Kumar, Vikas B. Thakare, A. K. Gupta, J. Acharya, Prabhat Garg

Abstract A three-layered composite wipe was fabricated by laminating individual layers of non-woven polypropylene, activated carbon fabric (ACF) and aramid fabric for the sampling and investigation of chemical warfare agents (CWA)-contaminated urban porous and non-porous surfaces. The material of main ACF layer was characterized to ascertain its suitability to act as an efficient adsorbent for the surface wipe sampling. The performance of ACF-based composite wipe was determined by evaluating its extraction efficiency, wiping efficacy and adsorption capacity for the sampling of blister and nerve agent class of CWA-contaminated surfaces using gas chromatography-mass spectrometry (GC-MS). Parameters like amount of wipe required, solvent selection, amount of solvent, time of extraction etc. were optimized to achieve the maximum recovery of contaminating analytes required for the forensic investigations. Overall recoveries of contaminating analytes after sampling and extraction were found to be in the range of 45–85% for all types of surfaces. No breakthrough in wiping process was noticed up to contamination density (CD) 1.6 mg/cm2 for non-porous surface and 3.2 mg/cm2 for porous surfaces. ACF-based wipe was found capable to significantly reduce the vapour hazards from liquid sulphur mustard (HD) and sarin (GB). Contamination from surfaces could be preserved within the wipe up to 15 days for the extended forensic investigation purposes. Limit of detections (LOD) of contaminants was determined in the range of 0.8–6.8 ng/cm2 while limit of quantitation (LOQ) was achieved up to the range of 2.4–14.4 ng/cm2 for wipe sampling of different surfaces. Graphical abstract

更新日期：2020-01-06
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
Aneta Vavrušová, Vladimír Vrkoslav, Richard Plavka, Zuzana Bosáková, Josef Cvačka

Fatty acid esters of long-chain hydroxy fatty acids or (O-acyl)-hydroxy fatty acids (OAHFAs) were identified for the first time in vernix caseosa and characterized using chromatography and mass spectrometry. OAHFAs were isolated from the total lipid extract by a two-step semipreparative TLC. The general structure of OAHFAs was established using high-resolution and tandem mass spectrometry of intact lipids and their transesterification and derivatization products. Two isomeric lipid classes were identified: O-acyl esters of ω-hydroxy fatty acids (ωOAHFA) and O-acyl esters of α-hydroxy fatty acids (αOAHFAs). To the best of our knowledge, αOAHFAs have never been detected in any biological sample before. Chromatographic separation and identification of OAHFAs species were achieved using non-aqueous reversed-phase HPLC coupled to electrospray ionization hybrid linear ion trap-Orbitrap mass spectrometry. The lipid species were detected as deprotonated molecules, and their structures were elucidated using data-dependent fragmentation in the negative ion mode. More than 400 OAHFAs were identified in this way. The most abundant ωOAHFAs species were 28:0/ω-18:2, 29:0/ω-18:2, 30:0/ω-18:2, 32:0/ω-18:2, and 30:0/ω-18:3, while αOAHFAs comprised saturated species 21:0/α-24:0, 22:0/α-24:0, 23:0/α-24:0, 24:0/α-24:0, and 26:0/α-24:0. OAHFAs were estimated to account for approximately 0.04% of vernix caseosa lipids.

更新日期：2020-01-06
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-06
Daniel A. Rickert, German A. Gómez-Ríos, Emir Nazdrajić, Marcos Tascon, Vathany Kulasingam, Janusz B. Pawliszyn

Immunosuppressive drugs (ISDs) are primarily administered following solid organ transplant or for treatment of a variety of autoimmune conditions. Their principal function is to suppress the activity of the immune system; however, the levels must be carefully monitored due to adverse effects of over- or underadministration. A technology for rapid quantitative screening, named coated blade spray (CBS), was directly coupled to a triple quadrupole mass spectrometer (MS/MS) to measure the concentration of ISDs (i.e., cyclosporine A, tacrolimus, everolimus, sirolimus) in whole blood samples. We evaluated the stability of replicate measurements over a 10-day period (precision), assessed linearity and limit of quantification, and performed a method comparison against a validated clinical immunoassay (Abbott ARCHITECT). Total interday variation of less than 5% for all target compounds at three different concentrations was achieved. The sensitivity of the method was determined as 0.25, 1, 1, and 2.5 ng/mL for everolimus, sirolimus, tacrolimus, and cyclosporine A, respectively. The concentrations of three immunosuppressive drugs in 284 patient samples (i.e., ~ 95 samples of cyclosporine A, tacrolimus, or sirolimus) obtained using the CBS-MS/MS methodology were compared with concentrations previously quantified on an Abbott ARCHITECT immunoassay system. Our analysis demonstrated significant statistical similarities between both methods. The results demonstrate that CBS-MS/MS is a suitable alternative to conventional methodologies for monitoring of ISDs from whole blood in a clinical setting.

更新日期：2020-01-06
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Nevena Klisara, Alagappan Palaniappan, Bo Liedberg

Abstract Efficient removal of interferents from complex matrices would significantly improve the performance of state of the art dipstick assays. Herein, we evaluate a graphitized carbon black (GCB)–incorporated dipstick, a configuration that has not been explored before, for reliable and facile on-site analysis of complex matrices. Carrot juice, a highly pigmented sample matrix, is chosen for evaluating the retention of interferents within the sorbent-incorporated cleanup pad on the dipstick. A peptide with a specific cleavage site for botulinum neurotoxin A light chain (BoNT/A LC), a model protease for validation of the proposed dipstick assay, is incubated with the test samples containing BoNT/A LC. Subsequently, the BoNT/A LC digested substrate and sample matrix flow vertically through the GCB-deposited cleanup pad within which the matrix interferents are captured, while the substrate, with a minimum of interferents, continues to flow toward a conjugation pad for labelling with Europium particles. Finally, the cleaved and uncleaved substrates flow toward a detection zone, where they bind to the test line producing a pinkish band which is not visible in the absence of GCB incorporation. The dipstick assay yields a LOD of 0.1 nM (5 ng/mL) of BoNT/A LC in carrot juice, within 20 min. The reported approach enables detection of proteases in a wide range of matrices upon incorporation of appropriate sorbents, ultimately aiming to exclude tedious laboratory-based sample pre-treatment protocols. Thus, merging extraction, cleanup, and pre-concentration steps with a sensitive optical detection approach is an attractive strategy for on-site assaying in complex matrices. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Li Yan, Xiaoye Wen, Zhefeng Fan

Abstract A fluorescence-enhanced sensor based on aggregation-induced emission (AIE) was synthesized using a di(2-picolyl)amine (DPA) group as a highly selective metal chelating agent for Zn2+. The combination of the probe and Zn2+ was achieved in an environment where the volume fraction of water was 90%, giving the probe good biocompatibility, and a large Stokes shift (100 nm) occurred after Zn2+ was combined with the probe. The obvious color change makes the probe visible to the naked eye, and gives it a high signal-to-noise ratio, and high contrast, and minimizes self-absorption. Because of the high selectivity of the DPA group to Zn2+, the sensitivity of the probe to detect Zn2+ has been improved. The mechanism of the formation of complexes between the probe and Zn2+ was confirmed by nuclear magnetic resonance spectroscopy (NMR), high-resolution mass spectrometry (HRMS), and particle size distribution. Under the optimal experimental conditions, the linear fluorescence reaction of Zn2+ was good, between 0.2 and 18 μM, and the detection limit was 1.3 × 10−7 M. The low toxicity and excellent membrane permeability of the probe in living cells enable it to be efficiently applied for Zn2+ imaging in cells. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Lei Zhang, Junping Wang, Jiankang Deng, Shuo Wang

Abstract In this study, a novel fluorescent “turn-on” aptasensor was developed for sensitive and rapid detection of tetracycline (TC) in animal-derived food. It is based on aptamer-functionalized nitrogen-doped graphene quantum dots (N-GQDs-aptamer) coupled with cobalt oxyhydroxide (CoOOH) nanoflakes. The CoOOH nanoflakes are efficient fluorescence quenchers in homogeneous solutions, and this is due to their advantages of excellent optical properties, superior flexibility, and water dispersibility. The proposed method’s mechanism is driven by quenching based on the fluorescence resonance energy transfer (FRET) between the donor (N-GQDs) and the acceptor (CoOOH nanoflakes). On the other hand, fluorescence recovery is caused by the structure switching behavior of the aptamer. Compared with previous methods, our developed method exhibits better behavior in terms of being easy to fabricate and being simple in detection procedure and maintains the detection limit low enough in TC determination: a linear range from 1 to 100 ng mL−1 and a detection limit of 0.95 ng mL−1 (S/N = 3). Furthermore, the proposed method was applied to five animal-derived food samples (milk, honey, fish, eggs, and chicken muscle) and demonstrated practical applicability. As well, the method has the advantages of simplicity in pre-treatment and convenience in instruments, saves times, and is cost-effective. Finally, the proposed method demonstrates significant potential for sensitive and rapid detection of specific components in real samples. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Li Yang, Honggang Nie, Fan Zhao, Shiyao Song, Ying Meng, Yu Bai, Huwei Liu

A novel online two-dimensional supercritical fluid chromatography/reversed-phase liquid chromatography–triple-quadrupole mass spectrometry (2D SFC/RPLC–QQQ MS) method based on a vacuum solvent evaporation interface was developed for lipid profiling in human plasma, in which lipid classes were separated by the first-dimension SFC and different lipid molecular species were further separated by the second-dimension RPLC. All separation condition parameters were carefully optimized, and their influence on the chromatographic behavior of lipids is discussed. Finally, the recoveries of 11 lipid standards were all more than 88% for the interface. Besides, the limit of detection for these lipid standards was on the order of nanograms per milliliter, and the relative standard deviations of the peak area and retention time ranged from 1.54% to 19.85% and from 0.00% to 0.10%, respectively. The final 2D SFC/RPLC–QQQ MS method allowed the identification of 370 endogenous lipid species from ten lipid classes, including diacylglycerol, triacylglycerol, ceramide, glucosylceramide, galactosylceramide, lactosylceramide, sphingomyelin, acylcarnitine, phosphatidylcholine, and lysophosphatidylethanolamine, in human plasma within 38 min, which was used for screening potential lipid biomarkers in breast cancer. The 2D SFC/RPLC–QQQ MS method is a potentially useful tool for in-depth studies focused on complex lipid metabolism and biomarker discovery.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Elisa Chiodi, Laura Sola, Dario Brambilla, Marina Cretich, Allison Marie Marn, M. Selim Ünlü, Marcella Chiari

Abstract Surface chemistry is a crucial aspect for microarray modality biosensor development. The immobilization capability of the functionalized surface is indeed a limiting factor for the final yield of the binding reaction. In this work, we were able to simultaneously compare the functionality of protein ligands that were locally immobilized on different polymers, while on the same solid support, therefore demonstrating a new way of multiplexing. Our goal was to investigate, in a single experiment, both the immobilization efficiency of a group of reactive polymers and the resulting affinity of the tethered molecules. This idea was demonstrated by spotting many reactive polymers on a Si/SiO2 chip and depositing the molecular probes on the spots immediately after. As a proof of concept, we focused on which polymers would better immobilize a model protein (α-Lactalbumin) and a peptide (LAC-1). We successfully showed that this protocol is applicable to proteins and peptides with a good efficiency. By means of real-time binding measurements performed with the interferometric reflectance imaging sensor (IRIS), local functionalization proved to be comparable to the classical flat coating solution. The final outcome highlights the multiplexing power of this method: first, it allows to characterize dozens of polymers at once. Secondly, it removes the limitation, related to coated surfaces, that only molecules with the same functional groups can be tethered to the same solid support. By applying this protocol, many types of molecules can be studied simultaneously and immobilization for each probe can be individually optimized.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Zhe Gao, Dezhi Yang, Yang Wan, Yaling Yang

Novel carbon dots (CDs) were synthesized by a one-pot hydrothermal approach using ampicillin as a precursor, and the as-prepared CDs exhibited a high quantum yield (23%). The CDs were found to possess abundant surface functional groups, thus providing good permeability to the cell, and the antibacterial activity of CDs was evaluated. S. aureus and L. monocytogenes were selected as model bacteria, and our results showed that the CDs exhibited antibacterial activity against S. aureus and L. monocytogenes under visible light illumination, even at low concentrations. The antibacterial mechanism is believed to be the production of reactive oxygen species (ROS) from CDs under visible light irradiation, which attacked the bacterial cell membranes, resulting in the death of the bacteria. In addition, because of the multicolor fluorescence properties of CDs, staining of S. aureus and L. monocytogenes obtained multicolor fluorescence images at different excitation wavelengths. Based on these results, CDs are a promising candidate material for biological applications.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-04
Hassan Refat H. Ali, Ahmed I. Hassan, Yasser F. Hassan, Mohamed M. El-Wekil

The study of biologically important Cu2+ and S2− ions has drawn great attention in the recent years since an abnormal level of these ions is an indication for health impairment. Therefore, a reliable strategy for effective fluorescence determination of Cu2+ and S2− ions was developed. Simply, the method based on economical plant-dependent thermolysis procedure for efficient green synthesis of water dispersible luminescent polyamine-based carbon dots (PA@C-dots) utilizes Vitis vinifera juice as precursor with a high quantum yield (32.1%) and good photo-stability. The fluorescent PA@C-dots were characterized by different spectroscopical, physical, and structural techniques. Furthermore, the synthesized PA@C-dots can be used as an efficient dual functional fluorescent probe for the sensitive and selective estimation of Cu2+ and S2− ions. The incorporation of Cu2+ ions and their adsorption on the surface of PA@C-dot skeleton leads to the respectable fluorescence quenching of C-dots (turn-off mode). The Cu2+-PA@C-dot was found to be sensitive to S2− ions. The addition of S2− recovers the fluorescence (turn-on mode) of Cu2+-PA@C-dots, thanks to its capacity for withdrawing Cu2+ from the shell of PA@C-dots. Fluorescence quenching in the range of 0.07–60 μM Cu2+ was obtained with LOD and LOQ of 0.02 and 0.066 μM, respectively. Sulfide detection provides linearity in the range of 0.8 to 95 μM with LOD and LOQ of 0.24 and 0.79 μM, respectively. The optimal excitation and emission wavelengths for all experiments are 435 nm and 498 nm, respectively. Experiment results elucidate that the proposed method is suitable for Cu2+and S2− ion detection in environmental water samples.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Drishya Rajan Parachalil, Jennifer McIntyre, Hugh J. Byrne

Abstract There is compelling evidence in the literature to support the application of Raman spectroscopy for analysis of bodily fluids in their native liquid state. Naturally, the strategies described in the literature for Raman spectroscopic analysis of liquid samples have advantages and disadvantages. Herein, recent advances in the analysis of plasma/serum in the liquid state are reviewed. The potential advantages of Raman analysis in the liquid form over the commonly employed infrared absorption analysis in the dried droplet form are initially highlighted. Improvements in measurement protocols based on inverted microscopic geometries, clinically adaptable substrates, data preprocessing and analysis and applications for routine monitoring of patient health as well as therapeutic administration are reviewed. These advances suggest that clinical translation of Raman spectroscopy for rapid biochemical analysis can be a reality. In the future, this method will prove to be highly beneficial to clinicians for rapid screening and monitoring of analytes and drugs in the biological fluids, and to the patients themselves, enabling early treatment, before the disease becomes symptomatic, allowing early recovery.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Zackery R. Roberson, Heather C. Gordon, John V. Goodpaster

Since its introduction, gas chromatography (GC) coupled to vacuum ultraviolet spectrophotometry (VUV) has been shown to complement mass spectrometry (MS) for materials such as petrochemicals, explosives, pesticides, and drugs. In forensic chemistry, opioids are commonly encountered but rarely are the samples pure. This work focuses on GC-VUV analysis applied to naturally occurring (e.g., morphine), semi-synthetic (e.g., heroin), and synthetic (fentanyl) opioids as well as common adulterants and diluents (e.g., lidocaine and quinine). The specificity of the VUV spectra were examined visually as well as via descriptive statistical methods (e.g., correlation coefficients and sums of square residuals). Multivariate pattern recognition techniques (principal component analysis and discriminant analysis (DA)) were used to prove the opioid spectra can be reliably differentiated. The accuracy of the DA model was 100% for a test set of VUV spectra. Finally, three “street” heroin samples were analyzed to show “real-world” performance for forensic analyses. These samples contained adulterants such as caffeine, as well as by-products of heroin manufacture.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Qiurong Luo, Xiujun Ren, Siping Wei, Yunchao Zheng, Die Gao, Qifeng Fu, Zhining Xia, Lujun Wang

Abstract Molybdenum disulfide quantum dots (MoS2 QDs) were chosen as a functional two-dimensional material to improve the separation performance of a traditional C18 column. In this work, MoS2 QDs were synthesized by the combination of sonication and solvothermal treatment of bulk MoS2. The prepared MoS2 QDs were characterized by transmission electron microscope (TEM), Zeta potential measurement, UV-visible absorption and fluorescence spectroscopy. Then, a novel MoS2 QDs embedded C18 (Sil-MoS2-C18) stationary phase was prepared for performing mixed-mode liquid chromatography. The results of elemental analysis (EA), thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) measurements indicated the stationary phase was prepared successfully. Five types of compounds including alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), nucleosides and nucleobases, anilines and flavonoids were utilized to evaluate reversed phase, weak cation exchange and hydrophilic interaction of the new column. To a certain extent, the column could achieve separation for different properties of samples on one column, with less organic solvent and shorter time than conventional alkyl and amino columns. Furthermore, the mechanism for separation was studied by investigating effects of mobile phase composition and pH on retentions. In summary, the Sil-MoS2-C18 stationary phase was deemed able to serve the performance of various types of phases, which revealed the prepared mixed-mode column could be potentially applied for the analysis of complex samples. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Chengnan Wang, Xia Gao, Shuo Wang, Yaqing Liu

Abstract Infections caused by foodborne microorganisms are a great threat to the global environment and public healthcare today. Thus, rapid, portable and sensitive assays that can realize the identification of foodborne bacteria are highly desired. In this study, a smart fluorescent and colorimetric dual-readout sensing system has been established for simple and rapid E. coli determination by utilizing the Cu2+-triggered oxidation of o-phenylenediamine (OPD). Initially, Cu2+ can oxidize OPD to OPDox, resulting in an orange-yellow fluorescence and visible pale-yellow color. However, E. coli can effectively reduce Cu2+ into Cu+, inhibiting the Cu2+-triggered oxidation of OPD to OPDox. Consequently, the introduction of E. coli can turn off both the fluorescence and the UV-vis absorbance signals of the OPD-Cu2+ system, illustrating an original mechanism for fluorescent and colorimetric dual-channel detection of E. coli. Moreover, a filter paper-based visual sensor was built and coupled with OPD-Cu2+ solution under the assistance of a UV lamp. The as-prepared sensor can detect E. coli quantitatively with the help of a typical smartphone color-scanning application (APP). Thus, this study offers a valid dual-mode assay for sensitive and on-site visible detection of E. coli, guaranteeing the reliability of the results and is more attractive for practical use. Graphical Abstract Schematic illustration of the smartphone-integrated sensing system for fluorescent and colorimetric dual-channel detection of E. coli based on the Cu2+-OPD system.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Mariosimone Zoccali, Daniele Giuffrida, Roberta Granese, Fabio Salafia, Paola Dugo, Luigi Mondello

Abstract The presence of carotenoids in human colostrum has been reported in the literature, and xanthophyll esters in human colostrum were recently detected for the first time. However, no published studies have reported whether apocarotenoids, which are metabolites derived from carotenoid enzymatic or nonenzymatic oxidative cleavage, are present in human colostrum. Therefore, the purpose of the present study was to search for the possible occurrence of apocarotenoids, including apocarotenoid esters, in human colostrum for the first time by applying an online supercritical fluid extraction–supercritical fluid chromatography–tandem mass spectrometry methodology. Recent evidence related to apocarotenoid transcriptional activity has suggested that they may have beneficial health properties superior to those of their parent carotenoids. Three different apocarotenoids, namely apo-8′-β-carotenal, apo-8′-lycopenal, and β-citraurin, were identified in intact human colostrum samples, with average concentrations of 85 nmol L−1, 54.6 nmol L−1, and 75.4 nmol L−1, respectively. The overall detection of 16 different free apocarotenoids and 10 different apocarotenoid fatty acid esters in human colostrum was achieved here for the first time. Their occurrence in human colostrum certainly has implications for newborn health status, since colostrum is the only form of food for the newborn during the very first days of life. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Zhi-Wei Wu, Xing-Chen Xie, Hong-Ran Guo, Huan Xia, Ke-Jing Huang

Abstract A tetrahedral DNA probe can effectively overcome the steric effects of a single-stranded probe to obtain well-controlled density and minimize nonspecific adsorption. Herein, a highly sensitive electrochemical biosensor is fabricated for determination of protein using a tetrahedral DNA probe and rolling circle amplification (RCA). N- and P-co-doped graphene (NP-rGO) is prepared, and AuNPs are then electrodeposited on it for DNA probe immobilization. Benefitting from the synergistic effects of the excellent electrical conductivity of NP-rGO, the stability of the tetrahedral DNA probe and the signal amplification of RCA, the biosensor achieves a low limit of 3.53 × 10−14 M for thrombin and a wide linear range from 1 × 10−13 to 1 × 10−7 M. This study provides a sensitive and effective method for the detection of protein in peripheral biofluids, and paves the way for future clinical diagnostics and treatment of disease. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Hongmei Liu, Ying Zhao, Anxiang Lu, Jin Ye, Jihua Wang, Songxue Wang, Yunxia Luan

We have developed an aptamer affinity column (AAC) for the purification and enrichment of trace aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) in genuine agro-products through the covalent conjugation of amino modified aptamer and NHS-activated Sepharose. The coupling and working conditions found to be suitable for this AFB-AAC were examined in regard to coupling time (2 min), loading volume (30 mL), and the methanol concentration (< 10%) used in the loading step. The performance of AFB-AAC was then further evaluated in terms of capacity (329.1 ± 13.7 ng for AFB1 and 162.5 ± 8.9 ng for AFB2), selectivity (excellent), reusability (twenty-three times for AFB1 and twelve times for AFB2), and repeatability (92.7% ± 2.9% for AFB1 and 71.5% ± 3.4% for AFB2). Furthermore, the AAC clean-up combined with HPLC-FLD demonstrated excellent linearity over a wide range, good sensitivity with an LOD of 50 pg mL−1 for AFB1 and 15 pg mL−1 for AFB2, and acceptable recovery with different spiking levels in different matrices. Finally, the AAC was successfully applied to analyte AFB1 and AFB2 in four types of agro-products as well as a maize flour reference material, and the results were found to be in accordance with those of commercial IACs. This study provides a reference for the analysis of other trace analytes by merely changing the corresponding aptamer and represents a strong contender for immune affinity columns.

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Jincan He, Zihui Zhong, Shiying Tan, Fuhai Wu, Yan Bai

Abstract It remains a problem for direct detection of small inorganic nitrite ions using resonance Rayleigh scattering (RRS) method based on the direct dye-binding reaction. In the present study, a redox-derivatization reaction taking only 5 min was introduced prior to nitrite detection. In the redox-derivatization reaction, nitrite ions were reduced by excess iodine ions to generate triiodide ions (I3−), which were further derivatized with a cationic dye (basic violet 1, BV1) to form the ion associates of I3−-BV1. Therefore, the RRS signal was significantly enhanced, resulting from the increase of particle size and resonance-enhanced scattering effect. The analytical procedure was performed by just mixing nitrite, oxidant, acid, and dye all-in-one, avoiding the tediousness of a multi-step process or the preparation of nanoparticles. The whole detection process including the redox-derivatization reaction was less than 6 min. The reaction conditions such as concentration of hydrochloric acid, potassium iodide, and BV1, reaction time, and temperature were investigated. Under optimum conditions, the concentration of nitrite was linear with an RRS signal of I3−-BV1 ion associates at 320 nm in the range of 0.015–1.2 mg/L. The limit of detection (LOD) was calculated to be 3.0 μg/L. The RRS method was applied to the determination of nitrite in real samples such as pork sausage, milk powder, and water with recovery of 95.2–112%. With advantages of rapidness, high sensitivity, and high selectivity, the method indicates potential applicability for detection of nitrite in complex samples. The method also provides an instructive protocol for detection of analytes that generate no/weak RRS enhancement after the direct dye-binding reaction. Graphical abstract

更新日期：2020-01-04
• Anal. Bioanal. Chem. (IF 3.286) Pub Date : 2020-01-03
Iva Ziu, Erving T. Laryea, Fayza Alashkar, Colin G. Wu, Sanela Martic

Abstract Neurodegeneration currently remains without a differential diagnosis or cure. Tau protein is one of the biomarkers of neurodegenerative diseases commonly known as tauopathies. Tau protein plays an integral role in stabilizing microtubules and cell structure; however, due to post-translational modifications, tau protein undergoes self-assembly into cytotoxic structures and is co-localized intra- and extracellularly. Hence, tau protein is a viable biomarker associated with protein pathogenesis and neurodegeneration. The novel optical biosensor for tau441 protein is based on the aptamer recognition probe and the biolayer interferometry (BLI) method for detection. The current biotin-aptasensor in combination with the streptavidin surface provides real-time monitoring of tau441 protein in the nanomolar range, with the limit of detection at 6.7 nM in vitro. The tau441 detection is achieved with high selectivity over other neurodegeneration biomarkers which include amyloid-β and α-synuclein. The aptasensor also allows for tau441 protein detection in a complex matrix such as fetal bovine serum, indicating its utility in other biological fluids for diagnostic applications. The optical method is simple, rapid and highly selective for point-of-care application which is critical for achieving the early and differential diagnosis of neurodegenerative diseases and identifying their treatments. Graphical abstract

更新日期：2020-01-04
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