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  • Extraction and preconcentration of organophosphorus pesticides from water samples and fruit juices utilizing hydroxyapatite/Fe3O4 nanocomposite
    Microchem. J. (IF 2.746) Pub Date : 2018-09-18
    Mohammad Chahkandi, Amirhassan Amiri, Seyedeh Roghayyeh Saadatdar Arami

    In this study, we demonstrate the application of newly developed magnetic potassium substituted hydroxyapatite (KHA/Fe3O4) for the extraction of organophosphorus pesticides (OPPs) from water samples. Nanoparticles of KHA were synthesized through an easy alkoxide–based sol–gel technique. The structure of nanocomposite was characterized by X–ray diffraction (XRD), Fourier transform infrared (FTIR) analysis, and energy dispersive X–ray analysis (EDXA). The OPPs were analyzed by gas chromatography–flame ionization detector (GC–FID). Variables affecting the performance of both extraction steps such as pH of the water sample, the sorbent amount, the desorption conditions, and the extraction time solvent were studied and optimized. Under optimum conditions, good linearity was achieved for all analytes in the 0.1–200 ng mL−1 concentration range. The limits of detection (at an S/N ratio of 3) are between 0.03 and 0.22 ng mL−1. The intra-day (n = 5) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 5.2–9.1% and 5.6–9.0%, respectively. The recoveries of OPPs from spiked real water samples and fruit juices are between 89.0 and 99.7%, with relative standard deviations between 5.5 and 10.8%.

    更新日期:2018-09-18
  • Preparation and characterization of magnetic metal–organic framework nanocomposite as solid-phase microextraction fibers coupled with high-performance liquid chromatography for determination of non-steroidal anti-inflammatory drugs in biological fluids and tablet formulation samples
    Microchem. J. (IF 2.746) Pub Date : 2018-09-15
    Roya Mirzajani, Fatemeh Kardani, Zahra Ramezani

    A novel solid-phase microextraction (SPME) fiber based on a capillary glass tube coated with magnetic Fe3O4/Cu3(BTC)2 metal organic frameworks nanocomposite was prepared by sol–gel technique. The magnetic Fe3O4/Cu3(BTC)2 metal organic frameworks nanocomposite were synthesized by a simple hydrothermal reaction and the resultant powder was mixed with sol–gel precursors to prepare sol–gel solution of the magnetic Fe3O4/Cu3(BTC)2 coating material. In this study, glass tubes with a specific diameter were used as substrates. The magnetic Fe3O4/Cu3(BTC)2 MOF nanocomposites coating was characterized using Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Then, the synthesized fiber as novel solid-phase microextraction (SPME) fiber combined with high-performance liquid chromatography (SPME–HPLC) was applied for the determination and quantification of non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, diclofenac, naproxen and nalidixic acid) in real samples including human urine, serum, plasma, and tablet formulation. To found optimum microextraction conditions, the influences of effective variables were investigated using one-factor-at-a-time experiments and the significant variables were optimized using a Box–Behnken design (BBD) combined with desirability function. Under optimized conditions, calibration graphs of analytes were linear in a concentration range of 0.1–400 μg L−1 with correlation coefficients >0.9966. Limits of detection and quantification were in the ranges of 0.03–0.0 5 μg L−1 and 0.12–0.18 μg L−1, respectively. This procedure was successfully employed in determining target analytes in spiked human urine, serum, plasma, and tablet samples with recoveries ranged from 94.0 to 102.0%.

    更新日期:2018-09-17
  • Sorption of Cr(III) from aqueous media via naturally functionalized microporous biochar: Mechanistic study
    Microchem. J. (IF 2.746) Pub Date : 2018-09-14
    Saima Batool, Muhammad Idrees, Mohammad I. Al-Wabel, Mahtab Ahmad, Kiran Hina, Hidayat Ullah, Liqiang Cui, Qaiser Hussain
    更新日期:2018-09-14
  • Determination of histamine in fish without derivatization by indirect reverse phase-HPLC method
    Microchem. J. (IF 2.746) Pub Date : 2018-09-13
    Muhammad Nadeem, Tayyab Naveed, Faisal Rehman, Zhongqi Xu

    Histamine (HA) is an important biochemical for human health and food quality. It is produced due to the decarboxylation of histidine. High level of HA was reported in a large number of fish tissues in Scombridae family. The presence of a low concentration of histamine is the indicator of the freshness of fish. Therefore, this study aims to develop a simple novel method for the quantification of histamine by revers-phase high-performance liquid chromatography (RP-HPLC-UV) followed by conventional UV detector at the wavelength of 205 nm. The extraction of the fish sample was optimized without derivatization, 2-5 dihydroxybenzoic acid (2-5 DHBA) and acetonitrile (ACN) was used in the mobile phase for the first time. Here we thoroughly investigate key experimental conditions such as UV absorbing probe, pH and mobile phase. We found that concentration of 6 mmol/L of 2,5-DHBA in the mobile phase, pH 2.65 and 50:50% ratios of 2,5-dihydroxybenzoic acid and acetonitrile were the suitable condition for determination of histamine in the fish sample. By applying our new method, we determine the HA concentration within 5 min. This novel method was validated by using different parameters like linearity, limit of detection (LOD), limit of quantification (LOQ), repeatability, matric effect, specificity, trueness, ruggedness, accuracy, precision, and specificity. The LOD and LOQ were 1 and 3 mg/kg respectively, and the correlation coefficient was >0.9995. We applied this method to the fish sample. Which were obtained from a local market here in Shanghai. Recovery was determined after spiking the fish sample; good recovery was observed with average recovery >82%. Thus, the proposed method provides a better reference for the successful analysis of fish safety, quality and trade.

    更新日期:2018-09-13
  • 更新日期:2018-09-13
  • A comparison study of chemiluminescence systems for the flow injection determination of silver nanoparticles
    Microchem. J. (IF 2.746) Pub Date : 2018-09-11
    Edyta Nalewajko-Sieliwoniuk, Julita Malejko, Anna Topczewska, Anatol Kojło, Beata Godlewska-Żyłkiewicz

    The comprehensive study of various chemiluminescence systems (luminol, lucigenin, KMnO4, Mn(IV), Ce(IV) and K3Fe(CN)6) in terms of their applicability to the detection of silver nanoparticles (AgNPs) has been carried out for the first time. Among the fourteen systems tested, Mn(IV)-formaldehyde-hexametaphosphate was selected as the optimal for the trace determination of AgNPs. The flow injection chemiluminescence method (FI-CL) based on enhancing effect of AgNPs on Mn(IV) chemiluminescence was developed. It was found that sensitivity of measurements depends on the size of AgNPs as well as the type of nanoparticles coating. Under the optimized conditions, the detection limits for AgNPs size fractions of 10 nm, 40 nm and 100 nm stabilized by sodium citrate were in the range 0.3–2.9 μg L−1, AgNPs size fractions of 40 nm, 60 nm and 100 nm stabilized by polyethylene glycol (PEG) were in the range 2.7–13.3 μg L−1, AgNPs size fractions of 20 nm and 75 nm stabilized by polyvinylpyrrolidone (PVP) were 20.2 μg L−1 and 24.9 μg L−1, respectively. Repeatability of the results expressed as a relative standard deviation (n = 10) was ≤3.3%. The developed method is simple and offers high sample throughput (150 samples per hour). The accuracy of the method was confirmed by analysis of the reference material RM 8017. The method was successfully applied to the direct determination of trace amounts of AgNPs in spiked natural mineral and tap water samples. The recoveries of AgNPs were in the range of 96.8–102%.

    更新日期:2018-09-12
  • Fabrication of a new electrochemical sensor based on AuPt bimetallic nanoparticles decorated multi-walled carbon nanotubes for determination of diclofenac
    Microchem. J. (IF 2.746) Pub Date : 2018-09-11
    Muhaned Mohammed Altai, Gholam Hossein Rounaghi, Behjat Deiminiat

    A new electrochemical sensor was developed for determination of diclofenac based on functionalized multi-walled carbon nanotubes (f-MWCNTs) and gold–platinum bimetallic nanoparticles (Au–PtNPs) modified gold electrode. The Au–PtNPs were deposited electrochemically on the surface of the f-MWCNTs modified electrode. The surface morphologies of the modified electrodes were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to evaluate the electrochemical properties of the constructed sensor. Under the optimized experimental conditions, the calibration curve was linear in the concentration range of 0.5 μM to 1000 μM of diclofenac and the detection limit was found to be 0.3 μM. The developed electrode also showed a high selectivity for diclofenac in the presence of the interfering species. The reproducibility, repeatability and stability of the electrode were satisfactory. The proposed electrochemical sensor was successfully employed for determination of diclofenac in real samples such as tablet and human urine samples.

    更新日期:2018-09-12
  • Photoacoustic spectroscopy with mica and graphene micro-mechanical levers for multicomponent analysis of acetic acid, acetone and methanol mixture
    Microchem. J. (IF 2.746) Pub Date : 2018-09-09
    Jan Suchánek, Pavel Janda, Michal Dostál, Antonín Knížek, Pavel Kubát, Petra Roupcová, Petr Bitala, Václav Nevrlý, Zdeněk Zelinger

    Multilayer graphene and mica cantilevers as part of an optical microphone in combination with CO2 laser emitting in the range of 9–11 μm were employed in a multicomponent analysis of a mixture of acetone, acetic acid and methanol by photoacoustic spectroscopy. Using these elements, the detection limits of mica circle cantilever were 0.54, 0.80 and 24.8 ppm for acetic acid, methanol and acetone, respectively; these limits were approximately 5 times lower than the detection limit of the highest-class microphone used in this study. The multicomponent analysis was performed using five selected CO2 laser lines and a classical method of least squares. Despite the inaccuracies of our system, very good agreement between the concentration of acetic acid calculated from the photoacoustic signal and from weighing of concentration standards (~3%) was found when measuring the signal in a 10:1:1 mixture of acetone:acetic acid:methanol at five selected laser lines. The absorption coefficient of acetic acid at 10.24 μm was almost 500 times higher than that of acetone, which showed the good ability of this method to detect acetic acid in a high background of acetone, which can be beneficial in the medical analysis of breath.

    更新日期:2018-09-10
  • Uptake and translocation monitoring of imidacloprid to chili and tomato plants by molecularly imprinting extraction - ion mobility spectrometry
    Microchem. J. (IF 2.746) Pub Date : 2018-09-09
    M.M. Aria, A. Sorribes-Soriano, M.T. Jafari, F. Nourbakhsh, F.A. Esteve-Turrillas, S. Armenta, J.M. Herrero-Martínez, M. de la Guardia

    The degradation of imidacloprid in soil and its uptake and translocation to chili and tomato plants was evaluated, as a proof of concept, of the possibilities of the combination of molecularly imprinted polymers (MIPs) and ion mobility spectrometry (IMS) for a fast and sensitive bioprocesses monitoring tool. To do it, a method based on the selective extraction of imidacloprid from soil and plant materials was developed. In the selected conditions, the MIP-IMS procedure provided a recovery of imidacloprid in soil and plant samples from 102 to 114%, for spiked concentration levels from 0.2 to 2.0 μg g−1. Precision of the methodology, expressed as the relative standard deviation (RSD) of a 100 and 1000 μg L−1 imidacloprid standard solution was 11 and 6%, respectively, being the RSD for the analysis of a soil sample spiked at a concentration level of 1 μg g−1 of 11% (n = 4). Limits of detection and quantification of 0.03 and 0.10 μg g−1 in the solid sample were also obtained, respectively. Regarding imidacloprid degradation, this study evidenced that the process follows a first order kinetics with a half-life between 39 and 45 days in soil, being necessary a growing period of 33 days before pesticide detection in stems and leaves.

    更新日期:2018-09-10
  • Determination of varenicline after photochemical fluorescence enhancement using spectrofluorimetry and high-performance liquid chromatography
    Microchem. J. (IF 2.746) Pub Date : 2018-09-08
    Alessandra Licursi M.C. da Cunha, Ana C.P. Osorio, Carlos A.T. Toloza, Joseany M.S. Almeida, Sarzamin Khan, Ricardo Q. Aucélio

    Photochemical derivatization (at 253 nm) of varenicline in alkaline medium (in NaOH 0.64 mol L−1) was successfully achieved aiming to induce strong fluorescence for quantitative purposes. The intense fluorescence from the produced photo-derivative covered a linear range of three orders of magnitude (10−8–10−6 mol L−1 range) allowing the spectrofluorimetric determination of the analyte in pharmaceutical formulations. For urine, the UV exposed sample was analyzed by high-performance liquid chromatography using borate buffer (0.01 mol L−1, pH 10.0). Separations were made using a C18 column with borate buffer (0.01 mol L−1, pH 10)/methanol (30:70% v/v) in isocratic elution. Detection limit was 2.5 × 10−7 mol L−1 for determination using HPLC. Measurement uncertainty was estimated and both methods were applied for the determination of varenicline in a pharmaceutical preparation and urine samples with acceptable recoveries using no expensive and toxic derivatization dyes.

    更新日期:2018-09-10
  • Thermodynamic and kinetics studies on adsorption of Indigo Carmine from aqueous solution by activated carbon
    Microchem. J. (IF 2.746) Pub Date : 2018-09-08
    Zahia Harrache, Moussa Abbas, Tounsia Aksil, Mohamed Trari

    The kinetic and equilibrium parameters of the quantitative adsorption for Indigo Carmine (IC) removed by commercial activated carbon (AC) were studied by UV–visible absorption spectroscopy. AC with a high specific surface area (1250.320 m2/g) was characterized by the Brunauer–Emmett–Teller (BET) method and point of zero charge (pzc).The effect of the initial dye concentration (10–60 mg/L), contact time (0–90 min), pH (1−12), agitation speed (0–600 rpm), adsorbent dose (1–10 g/L) and temperature (298–323 K) were determined to find the optimal conditions for a maximum adsorption. The adsorption mechanism of Indigo Carmine onto AC was studied using the first pseudo order, second pseudo order and Elovich kinetics models. The adsorptions kinetic were found to follow a pseudo second order kinetic model with a determination coefficient (R2) of 0.999. To get an idea on the adsorption mechanism, we applied the Webber-Morris diffusion model. The equilibrium adsorption data for Indigo Carmine on AC were analyzed by the Langmuir, Freundlich, Elovich, Dubinin and Temkin models. The results indicate that the Langmuir model provides the best correlation at 25 °C (qmax = 79.49 mg/g) and Dubinin at 40 °C (qmax = 298.34 mg/g). The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters such as free energy (ΔG° = −0.071 to −1.050 kJ/mol), enthalpy (ΔH° = 28.11 kJ/mol), entropy (ΔS° = 0.093 kJ/mol·K) and activation energy (Ea) of 51.06 kJ/mol of adsorption. The negative ΔG° and positive ΔH° values indicate that the overall adsorption is spontaneous and endothermic.

    更新日期:2018-09-10
  • Development of styrene-divinylbenzene copolymer beads using QuEChERS for simultaneous detection and quantification of 13 perfluorinated compounds in aquatic samples
    Microchem. J. (IF 2.746) Pub Date : 2018-09-08
    Yi Yin, Cheng Zhao, Guangming Zheng, Lichun Li, Shugui Liu, Qi Shan, Lisha Ma, Xinping Zhu
    更新日期:2018-09-09
  • Colorimetric detection of thioglycolic acid based on the enhanced Fe3+ ions Fenton reaction
    Microchem. J. (IF 2.746) Pub Date : 2018-09-08
    Yuanlin Huang, Tianran Lin, Li Hou, Fanggui Ye, Shulin Zhao

    Based on Fenton reaction without adding nanomaterials, a simple colorimetric sensor for detecting thioglycolic acid (TGA) was developed. By reducing Fe3+ ions to Fe2+ ions, TGA efficiently stimulates Fenton reaction through accelerating Fe3+/Fe2+ redox cycle. Owing to this, the accelerated decomposition of H2O2 generates more OH radicals, which cause a significant blue change in the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). Compared with Fe3+/H2O2/TMB system, this sensor can be operated over a wider pH range from 4.0 to 8.0. The calibration curve of TGA is achieved in the concentration range of 0.046–7.37 μg mL−1 under optimized conditions, and the detection limit of TGA is 0.036 μg mL−1 (S/N = 3). This sensor has been successfully applied to the detection of TGA in cold wave lotion with recovery rates between 99.1 and 101.6%, which has broad application prospects in cosmetic analysis and environmental monitoring.

    更新日期:2018-09-09
  • 更新日期:2018-09-09
  • Authenticity determination of tea drinks in the Chinese market by liquid chromatography coupled to isotope ratio mass spectrometry
    Microchem. J. (IF 2.746) Pub Date : 2018-09-03
    Bo Ding, Guangfeng Zeng, Zhiyuan Wang, Jianjun Xie, Lu Wang, Wenrui Chen

    Liquid chromatography coupled to isotope ratio mass spectrometry (LC-IRMS) was developed for determinations of caffeine δ13C from commercial tea in the Chinese market under lower temperature condition. On the basis of the carbon isotope analysis of 116 commercial tea samples including black tea, Oolong tea, green tea, dark tea, white tea, yellow tea and scented tea, it explained that the range of caffeine δ13C for commercial tea were from −26.14 to −33.68‰. Partial least-squares discriminant analysis (PLS-DA) modeling of caffeine δ13C data indicated that six main types of Chinese tea presented significant difference, and caffeine δ13C in Chinese tea was related to the fermented process except yellow tea. The method was also used for measurement of caffeine δ13C in the 19 tea drinks, and the results showed that caffeine in the seven tea drinks was not from the natural tea. Thus, LC-IRMS can be very promising tool for evaluation of natural caffeine from commercial tea and tea drinks authenticity.

    更新日期:2018-09-04
  • 更新日期:2018-09-03
  • An electrochemical aptasensor based on graphene doped chitosan nanocomposites for determination of Ochratoxin A
    Microchem. J. (IF 2.746) Pub Date : 2018-08-31
    Navpreet Kaur, Anu Bharti, Supriya Batra, Shilpa Rana, Shweta Rana, Aman Bhalla, Nirmal Prabhakar

    A simple and efficient functionalized graphene (f-graphene) doped chitosan (CS) based electrochemical aptasensor has been developed for ochratoxin A (OTA) detection. Use of f-graphene increased the electroactive surface area of the electrode and CS prevented leaching of the aptamer (APT) molecules. The dual properties of CS and f-graphene overall improved the sensor performance. The developed APT/SA/CS-f-graphene sensor has been characterized using Fourier Transform Infrared Spectroscopy (FTIR), Contact angle, Field emission - scanning electron microscopy (FE-SEM) and electrochemical studies. The aptasensor displayed OTA limit of detection (LOD) about 1 fg/mL for standard and 0.01 ng/mL for spiked sample within response time 8 min. The reusable aptaelectrode retained 85% of initial current values after 7th reaction with stability of about 7 days. Besides, real application of the fabricated aptasensor has been evaluated in the grape juice samples. Recoveries of OTA in the range of 90–101% were estimated successfully.

    更新日期:2018-09-03
  • In-syringe solvent-assisted dispersive solid phase extraction followed by flame atomic absorption spectrometry for determination of nickel in water and food samples
    Microchem. J. (IF 2.746) Pub Date : 2018-08-31
    Jamshid Mofid Nakhaei, Mohammad Reza Jamali, Shabnam Sohrabnezhad, Reyhaneh Rahnama

    This study presents a new in-syringe solvent-assisted dispersive solid phase extraction (ISSADSPE) method for determination of nickel ions in water and food. The method involved dispersion of a few milligrams of sorbent in the sample solution inside the barrel of a syringe through application of a disperser solvent. In less than 1 min, the extraction equilibrium was achieved due to dispersion of the sorbent and high mass transfer rate. Afterwards, syringe membrane was employed to separate the dispersed sorbent from the solution. Then the ethanol was withdrawn by syringe membrane to dissolve the analyte-enriched sorbent. Flame atomic absorption spectroscopy was applied to assess the obtained extract. Effective factors such as the sorbent nature and amount, sample volume, pH, ligand concentration, type and volume of disperser solvent and eluent, ionic strength and extraction time were evaluated and optimized to improve the extraction efficiency. Under optimized conditions (pH = 8.0, ligand concentration = 2.0 × 10−4, sorbent = 10 mg of benzophenone, disperser solvent 500 μL of ethanol), the limit of detection and quantification were found to be 0.7 μg L−1 and 2.0 μg L−1, respectively. The calibration curve kept its linearity from 2 to150 μg L−1, with the square correlation coefficient of 0.997. The relative standard deviation was measured as 2.5% while the enrichment factor was assessed as 50. The proposed method was successfully applied for determination of nickel in environmental water, spinach and celery samples, with recovery range of 97–101%.

    更新日期:2018-09-03
  • Determination of tranexamic acid in human plasma by UHPLC coupled with tandem mass spectrometry targeting sub-microgram per milliliter levels
    Microchem. J. (IF 2.746) Pub Date : 2018-08-31
    Luisa Barreiros, Júlia L. Amoreira, Sandia Machado, Sara R. Fernandes, Eduarda M.P. Silva, Paula Sá, Sibylle Kietaibl, Marcela A. Segundo

    Tranexamic acid (TXA) is an antifibrinolytic drug, with the ability to inhibit lysine binding at plasminogen receptors, used in adult trauma patients with on-going or at risk of significant haemorrhage. To understand the pharmacokinetics and pharmacodynamics of this drug in variable age groups undergoing surgeries with high blood loss, effective methods for determination of TXA in biological samples at sub-μg mL−1 are still required. We describe herein the development and validation of a method based on ultra-high performance liquid chromatography coupled to triple quadrupole-tandem mass spectrometry to quantify TXA in human plasma. An inexpensive, simple and efficient sample clean-up was implemented, not requiring matrix-matching calibration. Sample preparation consisted in protein precipitation using acetonitrile containing 0.5% (v/v) formic acid, followed by hydrophilic interaction based chromatographic separation, with elution in isocratic mode using a combination of acetonitrile and water (75:25, v/v), with quantification of TXA based on selected reaction monitoring. Good linearity was achieved (r2 > 0.997) for TXA concentrations ranging from 30 to 600 ng mL−1, with LOD of 18 ng mL−1 in plasma. The developed method proved to be selective, sensitive, accurate (96.4–105.7% of nominal values) and precise (RSD ≤ 4.5%). TXA was found to be stable in plasma extracts standing 24 h at room temperature (20 °C) or in the autosampler, and after three freeze-thawing cycles. Mean recovery values of TXA spiked plasma samples were ≥91.9%. No significant matrix effects were observed. The proposed methodology was successfully applied to the clinical study of plasma samples recovered during scoliosis surgery of pediatric patients pretreatment with TXA.

    更新日期:2018-09-03
  • An interesting strategy devoted to fabrication of a novel and high-performance amperometric sodium dithionite sensor
    Microchem. J. (IF 2.746) Pub Date : 2018-08-27
    Ali R. Jalalvand, Hector C. Goicoechea, Hui-Wen Gu

    According to the recently rumors about abusing of sodium dithionite (SDT) in baking bread by some bakers, we motivated to plan a study to fabricate an electrochemical SDT sensor. This work reports our results on fabricating a novel and high performance electrochemical sensor based on AuPd nanoparticles (AuPd NPs)/chitin-ionic liquid (Ch-IL)/ferrocene dicarboxylic acid‑carbon black-ionic liquid (FDCA-CB-IL)/glassy carbon electrode (GCE) to ultrasensitive determination of SDT in bread samples. The modifications steps were characterized with the help of cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. After characterization of the modifications, the sensor was electroanalytically characterized by chronoamperometry and the sensor was able to detect SDT in two linear ranges of 0.001–6 and 6–200 μM with a limit of detection of 0.1 nM and a sensitivity of 21.76 μA μM−1. After confirming the capability of the sensor for SDT determination in synthetic samples, it was applied to determination of SDT in three Iranian traditional bread samples and fortunately, there wasn't any SDT in the tested bread samples and to further investigation of the ability of the sensor, the real samples were spiked and good recoveries obtained which guaranteed a good performance for the fabricated sensor.

    更新日期:2018-08-31
  • Fully optimized new sensitive electrochemical sensing platform for the selective determination of antiepileptic drug ezogabine
    Microchem. J. (IF 2.746) Pub Date : 2018-08-30
    Mona A. Mohamed, Ahmed S. Fayed, Maha A. Hegazy, Nahla N. Salama, Enas E. Abbas

    The electrochemical oxidation of Ezogabine (EZG) based on Graphene Oxide Nanosheets (GO) and Ionic Liquids (IL)-modified carbon paste electrodes (CPE) has been studied using different techniques. GO and IL have a synergetic effect giving rise to highly improved electrochemical responses and provide an advantageous platform for the basis of an electrochemical sensor with excellent performance. Screening for the best experimental conditions was performed by fractional factorial design, while optimization studies were performed with the aid of central composite design. The optimum conditions were located by the use of Derringer's desirability function. The sensing of EZG via square wave voltammetry (SWV) is found to exhibit two wide linear dynamic ranges of 9.89 × 10−7–1.92 × 10−5 M and 1.92 × 10−5–2.0 × 10−4 M at pH 2.0. The limits of detection and quantification were calculated to be 9.86 × 10−8 and 3.28 × 10−7 M, respectively. The suggested sensor has been used successfully for EZG determination in human plasma as real samples. Satisfactory recoveries of analyte from these samples are demonstrated indicating that the suggested sensor is highly suitable for clinical analysis, quality control and a routine determination of EZG.

    更新日期:2018-08-31
  • Discrimination of Acacia gums by MALDI-TOF MS: Applications to micro-samples from works of art
    Microchem. J. (IF 2.746) Pub Date : 2018-08-30
    Clara Granzotto, Ken Sutherland, Julie Arslanoglu, Glen A. Ferguson

    This paper reports the discrimination of Acacia gums from the two most widely used and commercially significant species, A. senegal and A. seyal, using an innovative strategy based on matrix assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) after enzymatic digestion of the polysaccharide component. MALDI-TOF MS/MS experiments were carried out to determine the composition of the most intense ions of A. seyal gum and elucidate its mass fingerprint. The analytical method was applied to the analysis of gums from 12 other Acacia species and an attempt was made to find specific oligosaccharides that could be used to discriminate among them. Statistical analysis was performed to further explore the capability to differentiate these species. The implementation of a library of MALDI mass profiles of plant gums, with an initial focus on Acacia gums, represents the first MS-based attempt to facilitate reliable, species-level identification of these materials in unknown samples. The technique was successfully applied to the analysis of micro-samples from art objects of different types, with regard to geographical origin and date, including artefacts from ancient Egypt and a 20th century painting by Georges Braque, in the collections of The Metropolitan Museum of Art, New York, and the Art Institute of Chicago. Results demonstrated the possibility to detect Acacia gums from different species even in complex and aged micro-samples, providing important insights into the materials and condition of the objects. This research shows the potential to open new avenues of art historical and technical investigation into the specific plant sources, trade, and selection of materials by artists.

    更新日期:2018-08-31
  • Elemental analysis for iron, cobalt, copper and zinc decorated hydroxyapatite synthetic bone dusts by EDXRF and SEM
    Microchem. J. (IF 2.746) Pub Date : 2018-08-30
    O.K. Koksal, P. Wrobel, G. Apaydin, E. Cengiz, M. Lankosz, A. Tozar, I.H. Karahan, F. Özkalayci

    Iron, cobalt, copper and zinc decorated hydroxyapatite nanoparticles were produced with using ultrasonically assisted wet chemical method. Calcium nitrate tetra hydrate and dibasic ammonium phosphate were used as calcium and phosphorous source, respectively. Calcium nitrate tetra hydrate and dibasic ammonium phosphate solutions were prepared by dissolving the salts in distilled water and at different concentrations of decorated elements (iron, cobalt, copper and zinc) were appended to the calcium nitrate tetra hydrate solution. Stoichiometric decorated hydroxyapatite nanoparticles were analysed by energy dispersive X-ray fluorescence (EDXRF) with using standard method and the element analysis was determined with looking at the grain structures by Energy Dispersive X-Ray (EDX) and scanning electron microscopy (SEM). Not only have the concentrations of decorated metals but also calcium and phosphorus ratio for artificial bone powders been determined. As a result, calcium and phosphor ratio and metal decorated contents were evaluated according to the production values and compared previous studies. The answer to the question of how much of the contribution amounts was searched.

    更新日期:2018-08-31
  • Identification of NBOMe and NBOH in blotter papers using a handheld NIR spectrometer and chemometric methods
    Microchem. J. (IF 2.746) Pub Date : 2018-08-27
    Laiz de Oliveira Magalhães, Luciano Chaves Arantes, Jez Willian Batista Braga
    更新日期:2018-08-31
  • Monitoring of selected trace elements in sediments of heavily industrialized areas in Calcasieu Parish, Louisiana, United States by inductively coupled plasma-optical emission spectroscopy (ICP-OES)
    Microchem. J. (IF 2.746) Pub Date : 2018-08-27
    Derek Bussan, Austin Harris, Chris Douvris

    Located in Southwest Louisiana Calcasieu Parish is the home of several recent multibillion-dollar industrial projects creating a need for environmental monitoring projects. The monitoring of certain metals in the environment is important due to the toxic nature of these elements and the region's history of Superfund sites. Sediment samples were collected from seven locations around Calcasieu parish, and the concentrations of Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn were determined by ICP-OES. The locations were selected due to their proximity to industrialized locations. None of the sampled sediments exceeded the Louisiana Department of Environmental Quality regulations. All sampled locations had higher concentrations when compared to a non-industrialized location from the area. These differences may have been caused by anthropogenic factors.

    更新日期:2018-08-31
  • Comparative study of high performance liquid chromatography species-specific and species-unspecific isotope dilution inductively coupled plasma mass spectrometry. A case study of selenomethionine and the origin of its oxidized form
    Microchem. J. (IF 2.746) Pub Date : 2018-08-24
    Agnieszka Anna Krata, Marcin Wojciechowski, Jakub Karasinski, Ewa Bulska

    The analytical procedures for accurate quantification of selenomethionine (SeMet) at various concentration levels and in different matrix of certified reference materials (CRMs): ERM DB151 skimmed powder milk, ERM DC210a wheat flour and SELM 1 enriched yeast were developed and compared. Two modes of application of isotope dilution, namely species-specific isotope dilution analysis (IDA) and species-unspecific isotope dilution analysis with the use of high performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) were evaluated. The excellent results for SeMet were obtained in this study, using of developed species-specific ID HPLC ICP-MS and addition of spike solution before extraction. With this approach, the stability of SeMet during sample preparation or sample storage can be track. It was also possible to state the presence or absence of SeMet in oxidized form, which was co-eluted with the other selenium species. Moreover, the origin of SeMetO in extracts can be confirmed by the calculation and comparison of isotope ratios from SeMet and SeMetO signals. Equal altered isotope ratios in both species indicate that SeMetO was formed during extraction or storage of sample and SeMet is only source of SeMetO. Although, different isotopic ratios can indicate that the signal also comes from SeMetO already present in the sample. All results obtained for SeMet by species-unspecific ID HPLC ICP-MS, were close to the certified reference values within their uncertainty, under the condition, when 2-mercaptoethanol was added before extraction as antioxidant agent. The species-specific and species-unspecific IDA HPLC ICP-MS approaches were validated and both can be used to establish references values and accurate quantification of selenomethionine in food related products at various concentration level. Moreover, in the case of species-specific IDA, which although is much more time-consuming than species-unspecific IDA, the origin of SeMeO in extracts can be clearly indicated.

    更新日期:2018-08-31
  • Pesticide residues and heavy metals in commercially processed propolis
    Microchem. J. (IF 2.746) Pub Date : 2018-08-23
    M.I. González-Martín, I. Revilla, E.V. Betances-Salcedo, A.M. Vivar-Quintana
    更新日期:2018-08-31
  • Ultrasound-assisted solvent extraction of porous membrane packed solid samples: A new approach for extraction of target analytes from solid samples
    Microchem. J. (IF 2.746) Pub Date : 2018-08-29
    Muhammad Sajid, Mateusz Kacper Woźniak, Justyna Płotka-Wasylka

    For the first time, a porous membrane-based method is proposed for the extraction of target analytes directly from the solid samples. This method involves the packing of solid sample inside a porous polypropylene membrane sheet whose edges are heat-sealed to fabricate a bag. This bag is immersed in a suitable solvent and the analytes are extracted by the application of ultrasound energy. The various factors that affect the extraction performance such as extraction solvent, ultrasonication time, and ultrasound power are suitably optimized. The scope of this extraction method is very general, it can be used for the extraction of different classes of analytes from a variety of solid samples using suitable extraction solvents. The beauty of this method lies in the fact that only the small molecules such as analytes can pass through the membrane while the interfering or complex matrix species cannot pass through the membrane bag to the extraction solvent. Previously, the solid samples were first digested/dissolved into liquid medium and then analytes were extracted by membrane-protected adsorbents involving adsorption and desorption steps. With the proposed procedure, the steps of digestion/dissolution and the adsorption of analytes onto a suitable adsorbent are eliminated. Likewise, the steps of filtration, and centrifugation are not required as the solid is effectively packed inside the membrane bag. Moreover, the extraction device is low cost, portable, easy to fabricate, and simple to use in extraction process. In this work, proof of the concept is demonstrated by the extraction of polyaromatic hydrocarbons from the soil samples using GC–MS. This method provided reasonably low LODs ranging from 0.19 to 0.93 ng/mg. The inter-day precision ranged from 87.5 to 109%, while recoveries varied from 75.1 ± 4.9 to 106.0 ± 4.5%.

    更新日期:2018-08-30
  • Selective and fast screening method for inorganic arsenic in seaweed using hydride generation inductively coupled plasma mass spectrometry (HG-ICPMS)
    Microchem. J. (IF 2.746) Pub Date : 2018-08-28
    Ásta H. Pétursdóttir, Helga Gunnlaugsdóttir

    A method for the determination of inorganic arsenic (iAs) without chromatography using hydride generation — inductively coupled plasma mass spectrometry (HG-ICPMS) is applied to 40 brown macroalgae samples (Fucus vesiculosus, Ascophyllum nodosum, Saccharina latissima). Determining iAs in seaweed matrices is a challenge and, in this study, using 2% HNO3 and 3% H2O2 extraction media the HG-ICPMS outperformed the most commonly used method of HPLC-ICPMS for the determination of iAs in the seaweed samples. There was a good comparison between the simple and fast HG-ICPMS and the more accurate but time-consuming HPLC-HG-ICPMS. Linear regression showed reasonable linearity (R2 of 0.82), with a slope slightly higher than 1 (1.15 ± 0.09) and intercept 0.03 ± 0.01 when comparing the concentrations of iAs determined with the two methods. Hence there is a minor overestimation of iAs with HG compared to the HPLC-HG, however, the method is well suited as a quick screening method. The iAs concentration was below 1% of total arsenic concentration for all the seaweed samples irrespective of using HG-ICPMS or HPLC-HG-ICPMS.

    更新日期:2018-08-30
  • A new method for spectrophotometric determination of carbaryl based on rubber tree bark peroxidase enzymatic reaction
    Microchem. J. (IF 2.746) Pub Date : 2018-08-28
    Sam-ang Suphareok, Kraingkrai Ponhong, Watsaka Siriangkhawut, Kate Grudpan
    更新日期:2018-08-29
  • Removal of reactive yellow 15 from water sample using a magnetite nanoparticles coated with covalently dimethyl octadecyl[3-(trimethoxysilylpropyl)]ammonium chloride ionic liquid
    Microchem. J. (IF 2.746) Pub Date : 2018-08-28
    Farhad Golmohammadi, Mahnaz Hazrati, Meysam Safari

    Magnetic nanoparticles modified with the ionic liquid were prepared. The kinetics, adsorption isotherms, thermodynamics and spectroscopic analyses of the removal of the reactive yellow 15 by ultrasound assisted adsorption onto magnetic nanoparticles were investigated. Several variables affecting the removal of the reactive yellow 15 include amount of sorbent, pH, ultrasonic power and reaction time, salt concentration, and desorption conditions were studied and optimized. Three kinetic models were studied to analyze the adsorption mechanism. It was found that the adsorption kinetics followed a pseudo-second-order model for the dye concentration range studied in this study. Dye adsorption equilibrium data were well fitted to the Langmuir isotherm and the maximum monolayer capacity qmax was calculated from the Langmuir as 63.69 mg g−1. A thermodynamic parameter was studied by the Gibbs free energy function. The results obtained showed that the MNP modified with the IL is an appropriate adsorbent for removal of reactive yellow 15 from waste water.

    更新日期:2018-08-29
  • Effective tuning guanidinium ionic liquid as greener solvent for fast and sensitive determination of auxin herbicides
    Microchem. J. (IF 2.746) Pub Date : 2018-08-28
    Chen Fan, Jiale Yang, You Liang, Hongqiang Dong, Wenbing Zhang, Gang Tang, Yongsong Cao
    更新日期:2018-08-29
  • Optimization of a modified QuEChERS method by means of experimental design for multiresidue determination of pesticides in milk and dairy products by GC–MS
    Microchem. J. (IF 2.746) Pub Date : 2018-08-28
    Özün Görel Manav, Şule Dinç-Zor, Güzin Alpdoğan

    The aim of this study is to determine optimum extraction and clean up conditions for different pesticide residues in milk and dairy products by using GC–MS. A Box-Behnken design with 3-level 4-variable followed by Plackett-Burman screening design was employed in order to optimize significant variables of the modified QuEChERS method. After the determination of optimal experimental conditions, the proposed method was validated according to SANCO guideline. The method presented recoveries between 72.5% and 120.0% for 25 pesticides, which is satisfactory when one considers the performance criteria detailed in this guideline. The repeatability and within-laboratory reproducibility ranged from 0.95 to 14.62% and from 1.45 to 17.94%, respectively. Also, the method allowed the determination at low detection limits within short analysis time (<17.5 min). Consequently, application of the developed method to milk and dairy products samples revealed that this method is suitable for routine multi-residue pesticides analysis in terms of high accuracy, precision and efficient.

    更新日期:2018-08-29
  • 更新日期:2018-08-27
  • Reliable quantification of trace diarrhetic shellfish poisoning toxins in high-lipid bivalves by UHPLC-ESI-MS/MS in time segment polarity switching mode: Comparison of three extraction methods
    Microchem. J. (IF 2.746) Pub Date : 2018-08-25
    Myoung Eun Lee, Keon-hee Ko, Na-Hyun Park, Wonwoong Lee, Hye Hyun Yoo, Jeongmi Lee, Yong Seok Choi, Jongki Hong

    Analysis of marine biotoxins in high-lipid bivalves has several limitations due to the coexistence of lipid matrices, low biotoxin concentrations, and the different physiochemical properties of the various biotoxins. In this study, a sensitive and reliable method to simultaneously determine six diarrhetic shellfish poisoning (DSP) toxins (five acidic and one neutral biotoxins) in oysters and mussels was developed based on UHPLC-MS/MS-multiple ion reaction monitoring (MRM) using time segment polarity switching. For effective sample pretreatment, three protocols including syringe filtration, Strata™-X solid phase extraction (SPE), and freezing lipid filtration combined with SPE (FLF + SPE) were evaluated, and FLF + SPE method was shown to be the most effective with high lipid removal efficiency. Aging effects of the UHPLC mobile phase on MS detection sensitivity and retention time shift of DSP toxins were carefully examined. The developed method provided good recoveries ranging from 81.0 to 119.6%, showing no significant matrix effect and assay was linear with coefficients of determination above R2 > 0.99 for all analytes. Validation tests using a certified reference material (CRM) and spiking DSP toxins (OA and DTX-1 at 1.07 μg/g, and DTX-2 at 0.86 μg/g) showed this method to be acceptable, with a relative standard deviation of <0.17% and recovery ranging from 87.29 to 109.97%. Finally, the established method was successfully applied to quantify DSP toxins in 40 oyster and mussel samples collected from Korean fishery markets, ensuring sea food safety.

    更新日期:2018-08-26
  • Comparison of structure, morphology, and topography of fertilizer-based explosives applied in the mining industry
    Microchem. J. (IF 2.746) Pub Date : 2018-08-25
    Andrzej Biessikirski, Łukasz Kuterasiński, Michał Dworzak, Jóżef Pyra, Michał Twardosz

    Samples of ANFO and an explosive matrix were studied using IR spectroscopy, X-ray diffraction, and scanning electron microscopy to compare their structure, morphology, along with topography. IR and SEM analyses of ANFO showed that ammonium nitrate used for the manufacturing of this type of explosive has the same structure but different morphology, which is dependent on provenance. The results of XRD, IR and SEM analyses for both tested samples of the emulsion explosive matrix have shown that its chemical composition has a major impact on their structure, morphology, and topography. The observed differences are due to the different composition of the dispersed phase and/or applied methodology during the preparation of the emulsion matrix.

    更新日期:2018-08-26
  • Ni3S2/ionic liquid-functionalized graphene as an enhanced material for the nonenzymatic detection of glucose
    Microchem. J. (IF 2.746) Pub Date : 2018-08-25
    Feng Luan, Shuang Zhang, Dandan Chen, Fanmei Wei, Xuming Zhuang
    更新日期:2018-08-26
  • Assessment of sorption capability of montmorillonite clay for lead removal from water using laser–induced breakdown spectroscopy and atomic absorption spectroscopy
    Microchem. J. (IF 2.746) Pub Date : 2018-08-25
    E.J. Terán, M.L. Montes, C. Rodríguez, L. Martino, M. Quiroga, R. Landa, R.M. Torres Sánchez, D.M. Díaz Pace

    Laser–induced breakdown spectroscopy (LIBS) and atomic absorption spectroscopy (AAS) techniques were applied for quantitative analysis of the remaining Pb content in water samples after treatment with a raw montmorillonite (MMT) and an organic derivative (MMO) clays for heavy metal removal, an issue of crucial importance for decontamination of water bodies. The Pb sorption capabilities of MMT and MMO clays were assessed by using solutions with known Pb concentrations, in the range 100–500 ppm. To carry out the LIBS analysis, the samples were prepared in the form of solid pellets with powdered calcium hydroxide addition. The measurement conditions were optimized to achieve reliable analytical results and the plasma parameters, i.e., temperature and electron density, were obtained. For quantification purpose, a calibration curve was constructed with the Pb I emission line at 4057.8 Å measured at the time window 30–45 μs by using reference samples with Pb concentrations in the range 56–715 ppm. The Pb residual content in the liquid samples determined with LIBS showed a good agreement with those measured with AAS. The sorption efficiency of Pb from contaminated water was calculated through a sorption percentage SPb%. The calculated SPb% was higher for MMT (56%–100%) than for MMO (27%–47%). The results also demonstrated the usefulness of LIBS method for the determination of Pb concentrations in liquid samples.

    更新日期:2018-08-26
  • Highly sensitive and selective fluorescent sensor for tetrabromobisphenol-A in electronic waste samples using molecularly imprinted polymer coated quantum dots
    Microchem. J. (IF 2.746) Pub Date : 2018-08-24
    Jingwen Feng, Yun Tao, Xiaoli Shen, Hua Jin, Tingting Zhou, Yusun Zhou, Liqin Hu, Dan Luo, Surong Mei, Yong-Ill Lee

    In this study, an optosensing composite was fabricated by coating a molecularly imprinted polymer (MIP) layer onto CdTe quantum dots (MIP-QDs) to develop a fluorescent sensor for the determination of tetrabromobisphenol-A (TBBPA). The resulting MIP-QDs composite was well characterized and had ideal properties of morphology and photoluminescence. Under the optimized experiment conditions, this fluorescent sensor exhibited a good linearity with TBBPA covering the concentration range of 1.0–60.0 ng/mL and the detection limit was as low as 3.6 ng/g. This developed MIP-QDs sensor was successfully employed to detect TBBPA in electronic waste (e-waste) samples for the first time. The mean recoveries were in the range from 89.6% to 107.9% with the relative standard deviation below 6.2%, which were in accordance with the results of HPLC-UV method. The average concentration of TBBPA in electric fan and circuit board samples were 260.20 and 707.30 mg/kg, respectively. This study provided a simple, rapid, highly sensitive and selective method to detect TBBPA in e-waste samples.

    更新日期:2018-08-24
  • Amperometric biosensor based on laccase immobilized onto a nanostructured screen-printed electrode for determination of polyphenols in propolis
    Microchem. J. (IF 2.746) Pub Date : 2018-08-24
    Lina Mohtar, Pedro Aranda, Germán A. Messina, Mónica A. Nazareno, Sirley V. Pereira, Julio Raba, Franco A. Bertolino

    This work describes the preparation of an electrochemical biosensor for polyphenols determination in propolis samples. The biosensing scheme is based on a nanocomposite film of laccase enzyme (Lac) immobilized on gold nanoparticles (AuNPs) electrodeposited in a screen-printed carbon electrode (SPCE) modified with polypyrrole (Ppy) through an in-situ electropolymerization. The electrodeposition of the AuNPs increases the available area for Lac immobilization. The nanocomposite film (Ppy/Lac/AuNPs/SPCE) was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry. Polyphenols were detected in ethanolic extracts of propolis (EEP), where in presence of the Lac oxidized to the polyphenols, and so they can be reduced on the Ppy/Lac/AuNPs/SPCE by amperometry at −450 mV vs Ag/AgCl. The calibration plot showed a linear response in the concentration range from 1 to 250 μM expressed as caffeic acid, with a limit of detection of 0.83 μM. The time required for analysis was 15 min, compared to the time (85 min) by spectrophotometric methods, especially the so-called Folin-Ciocalteu method. The method exhibited good selectivity, stability and reproducibility for detecting polyphenols in propolis samples.

    更新日期:2018-08-24
  • Micropaper-based analytical device (μPAD) for the simultaneous determination of nitrite and fluoride using a smartphone
    Microchem. J. (IF 2.746) Pub Date : 2018-08-24
    Ezequiel Vidal, Anabela S. Lorenzetti, Adriana G. Lista, Claudia E. Domini
    更新日期:2018-08-24
  • 更新日期:2018-08-24
  • 更新日期:2018-08-21
  • Magnetic covalent organic frameworks based on magnetic solid phase extraction for determination of six steroidal and phenolic endocrine disrupting chemicals in food samples
    Microchem. J. (IF 2.746) Pub Date : 2018-08-21
    Ning Li, Di Wu, Jichao Liu, Na Hu, Xuexiang Shi, Chunji Dai, Zhiwei Sun, Yourui Suo, Guoliang Li, Yongning Wu

    A simple and rapid magnetic covalent organic frameworks based on magnetic solid phase extraction method was proposed for effective determination of six steroidal and phenolic endocrine disrupting chemicals in meat samples. Fluorescence labeling combined with high performance liquid chromatography fluorescence detection was used to quantify endocrine disrupting chemicals. Covalent organic frameworks could be a wonderful choice as sorbent for endocrine disrupting chemicals enrichment due to its characteristics of large specific surface area, great structure stability and functional properties. In this work, COF(TpBD) was chosen as functionalized groups to be grafted onto the surface of Fe3O4 microspheres via one-step surface fabrication strategy. The parameters affecting the extraction efficiency were investigated in detail. The adsorption equilibrium was achieved within 5 min. Under the optimized conditions, the obtained Fe3O4@COF(TpBD) materials showed excellent extraction performance for endocrine disrupting chemicals with high sensitivity (1.4–8.7 μg L−1 for LODs and 4.6–29.0 μg L−1 for LOQs) and good linearity (R ≥ 0.9986). Determination of endocrine disrupting chemicals in meats was achieved using the proposed method. Furthermore, the method, validated on spiked meats (including chicken, pork and shrimp), showed satisfactory accuracy, with average recoveries in the 89.6–108.9% range and relative standard deviations ≤6.3%. Additionally, two kinetic models were investigated to recognize the target analytes adsorption mechanism onto Fe3O4@COF(TpBD) materials, and the results indicated that the pseudo-second-order model was the most suitable in describing the adsorption kinetics of endocrine disrupting chemicals on the Fe3O4@COF(TpBD) materials. The proposed method was proved to be feasible for the determination of endocrine disrupting chemicals in complex food samples.

    更新日期:2018-08-21
  • Determination of acidic, basic and amphoteric drugs in biological fluids and wastewater after their simultaneous dispersive micro-solid phase extraction using multiwalled carbon nanotubes/magnetite nanoparticles@poly(2-aminopyrimidine) composite
    Microchem. J. (IF 2.746) Pub Date : 2018-08-21
    Niloofar Jalilian, Homeira Ebrahimzadeh, Ali Akbar Asgharinezhad

    Determining of acidic, basic and amphiprotic drugs from different samples simultaneously is a remarkable and discussible topic in sample preparation methods. In this work, an easy and fast dispersive micro-solid phase extraction (D-μ-SPE) method was developed using a magnetic multiwalled carbon nanotubes/Fe3O4@poly(2‑aminopyrimidine) (MWCNTs/Fe3O4@PAPy) as a viable and efficient sorbent to preconcentrate and determine five model analytes in three different classes (nortriptyline, cetirizine, naproxen, diclofenac and ibuprofen). The nanosorbent was characterized by diverse characterization techniques. After the extraction step, HPLC-photo diode array detection (HPLC-DAD) was employed to quantify the model analytes. The effects of various parameters on the dispersive magnetic solid phase extraction method were explored thoroughly via design of experiment and desirability function. The highest extraction performance was obtained under the conditions of: a sample pH of 2, a sorbent amount of 8 mg, a sorption time of 5 min, a salt concentration of 20% w/v in the sample solution, 120 μL 0.01 mol L−1 HCl in acetonitrile as an eluent, and an elution time of 2 min. By employing the optimum conditions detection limits and linear dynamic ranges were obtained in the range of 0.07–3.5 μg L−1 and 0.25–1500 μg L−1, respectively. The relative standard deviations (n = 5) were between 1.4% and 10.5%. Eventually, this method was simply applied for determination and extraction of target analytes in different samples.

    更新日期:2018-08-21
  • 更新日期:2018-08-21
  • Corrosion products and microstructure of copper alloy coins from the Byzantine-period Ma'agan Mikhael B shipwreck, Israel
    Microchem. J. (IF 2.746) Pub Date : 2018-08-20
    A. Inberg, D. Ashkenazi, M. Cohen, N. Iddan, D. Cvikel

    Seven coins, covered with black concretion coating, found in the Byzantine-period Ma'agan Mikhael B shipwreck, were examined in this study. Metallurgical methods comprising visual testing, XRF, multi-focal light microscopy, SEM-EDS analysis and Raman spectroscopy, were used to determine the corrosion products and microstructure of the coins. The analysis results show that the coins were made of copper-lead alloy with a heterogeneous microstructure of bright and dark metal areas. The external surfaces of the coins were mostly composed of oxides and corrosion product compounds rich in Cu, Pb and Sn, while the external dark concretion coating was rich in Si, S, Ca and C compounds. Gradual variation of the composition and structure of the oxides and concretion coating layers was observed.

    更新日期:2018-08-20
  • Probing the antigen-antibody interaction towards ultrasensitive recognition of cancer biomarker in adenocarcinoma cell lysates using layer-by-layer assembled silver nano-cubics with porous structure on cysteamine caped GQDs
    Microchem. J. (IF 2.746) Pub Date : 2018-08-18
    Mohammad Hasanzadeh, Samira Rahimi, Elham Solhi, Ahad Mokhtarzadeh, Nasrin Shadjou, Jafar Soleymani, Soltanali Mahboob

    The incidence of breast cancer has been increasing over the years. To control and monitor this disease several tumor biomarkers have been proposed for early diagnosis, patient follow-up and/or treatment guidance. The only serum breast cancer biomarker in current use is the cancer antigen 15-3 (CA 15-3). Highly sensitive and label-free detection of the biomarker carbohydrate antigen 15-3 (CA 15-3) remains a challenge in the diagnosis of breast cancer. Here, a novel electrochemical immunosensor capable of sensitive and label-free detection of CA 15-3 is reported. This unique immunosensor, equipped with a highly conductive nanocomposite (i.e., thiolated graphene quantum dots modified silver nanocubics (Ag NCs)-modified electrode, exhibited significantly increased electron transfer and high sensitivity towards CA 15-3. This novel immunosensor, with a limit of detection 0.019 U/mL, worked well over two linear range of 0.095–0.5 and 0.25–1 U/mL. Unlike conventional immunosensors, which usually involve complicated label processing and time consuming separations, the use of highly conductive graphene avoids the need for labels and is simple in nature. The strategy developed for this immunosensor provides a promising approach for clinical research and diagnostic applications.

    更新日期:2018-08-20
  • Feasibility of measuring Cr(III) and Cr(VI) in water by laser-induced breakdown spectroscopy using ceramics as the solid support
    Microchem. J. (IF 2.746) Pub Date : 2018-08-18
    Alexandrina A.C. Carvalho, Daniel M. Silvestre, Flávio O. Leme, Juliana Naozuka, Danielle P. Intima, Cassiana S. Nomura

    Laser-induced breakdown spectroscopy (LIBS) is a multi-elemental technique with multiple advantages. However, direct determination in liquid samples is not an easy task since laser water interaction can affect the precision and accuracy of the method and cause loss of sensitivity. To enable LIBS application in liquid sample analysis, some strategies such as liquid-to-solid transfer have been used. This work proposes the quantification of chromium in water samples by LIBS using ceramic as the solid support. Results showed that the ceramic selectively adsorbs Cr(III) species at pH 7 and quantification of Cr(VI) species by LIBS was also possible after reduction of this species to Cr(III) using Fe(II) as the reducing agent. Instrumental parameters were optimized, and the best conditions found included a 65 μm spot size, 430 accumulated pulses with 20 mJ pulse−1, and 0.75 ms of delay time. Calibration was carried out with synthetic calibration standards prepared by adsorption of increasing concentrations of chromium in ceramic. Tap water samples spiked with 0.9 mg L−1 of Cr(III) and 0.1 mg L−1 of Cr(VI) were analysed by the proposed method and recoveries of 105 ± 2% and 103 ± 3% were obtained for Cr(III) and Cr(VI), respectively.

    更新日期:2018-08-20
  • A BiFEs-based SWASV method for fast screening of multi-heavy metals in Xiaochaihu Tang
    Microchem. J. (IF 2.746) Pub Date : 2018-08-18
    Rong Wang, Dandan Kong, Jiaojiao Yao, Xiaowen Dou, Yufeng Huang, Shihai Yang, Meihua Yang

    Multi-heavy metal residues in traditional Chinese medicines especially their formulas have become a world-wide concern for human's health. A real time analysis of multi-heavy metals with high sensitivity and accuracy is of great necessity. In this study, an anodic square wave stripping voltammetry (SWASV) technique based on the stable Bismuth material was developed for the fast screening of Cd2+, Pb2+ and Cu2+ in Xiaochaihu Tang for its safe medication in practice. Firstly, a flat and compact Bismuth film electrode (BiFE) was prepared by pre-plating Bi crystal on glass carbon electrode (GCE) substrate at special deposition potential and deposition time, which was confirmed through the observation of morphological and electrochemical properties. Then, the heavy metals of interest were isolated from complex Xiaochaihu Tang by using an optimized digestion system and a low-cost sample preparation procedure. Besides, three different deposition potentials were selected to respectively reduce 3 kinds of cations for a better reproducibility and accuracy of the analysis than before. It was demonstrated that the intensity of the remarkable anodic peaks of Cd2+, Pb2+ and Cu2+ at −0.876 V, −0.621 V and − 0.248 V were proportional (R2 = 0.9975, 0.9993, 0.9997) to their concentrations in the decoction electrolyte in the range of 0.008–0.08 μg·mL−1 for Cd2+, 0.01–0.1 μg·mL−1 for Pb2+ and 0.10–1.00 μg·mL−1 for Cu2+, respectively. The developed SWASV method allowed low detection limits of 0.0031 μg·mL−1, 0.0002 μg·mL−1 and 0.0044 μg·mL−1 for Cd2+, Pb2+ and Cu2+, which are much lower than the guideline values in herbs set in the Chinese Pharmacopeia. Real sample analysis showed that Pb2+ was detected in 3 batches of Xiaochaihu Tang samples within 5 min, which were confirmed by the ICP-MS method. Therefore, this developed method can be applied in the fast screening of multi-heavy metals in complex decoction matrices.

    更新日期:2018-08-18
  • Classifying impurity ranges in raw sugarcane using laser-induced breakdown spectroscopy (LIBS) and sum fusion across a tuning parameter window
    Microchem. J. (IF 2.746) Pub Date : 2018-08-18
    Wesley Nascimento Guedes, Fabíola Manhas Verbi Pereira

    The presence in raw sugarcane of low levels of solid impurities from soil particles and green and dry/brown sugarcane leaves is relevant to improving sugar mill production performance. Two ranges of impurities for raw sugar manufacturing processes need to be characterized from 0 to 5 wt% (desired material) and 8 to 10 wt% (undesired material); these ranges are denoted as 1 and 2, respectively. Laser-induced breakdown spectroscopy (LIBS) combined with chemometrics is used to detect chemical elements and different impurity ranges in leached raw sugarcane solutions. The potential use of LIBS based on leached solutions immobilized in a polyvinyl alcohol (PVA) polymer requires approximately 2 h sample preparation time. LIBS data are assigned to the above two impurity ranges using fusion of multiple classifiers. Most classifiers require a training set and optimization of a tuning parameter to select the best model; however, the sum fusion across a tuning parameter window used for classifying the samples in this study is a process that does not require either. The classification results are 97% accuracy for both ranges; 94% and 100% specificity for ranges 1 and 2, respectively; and 100% and 94% sensitivity for ranges 1 and 2, respectively. The classification results indicate potential for future applications in sugarcane refineries.

    更新日期:2018-08-18
  • Development of a portable 3D-printed flow-through passive sampling device free of flow pattern effects
    Microchem. J. (IF 2.746) Pub Date : 2018-08-18
    Fidelis Nitti, M. Inês G.S. Almeida, Richard Morrison, Robert W. Cattrall, Vincent J. Pettigrove, Rhys A. Coleman, Spas D. Kolev

    A low cost and portable flow-through passive sampling device (PSD) which is not affected by the flow pattern of the sampled aquatic system was developed. Zn2+ was selected as the target analyte in optimizing and testing the device under laboratory conditions using as the source solution (SS) either Zn2+ solutions or environmental waters, spiked with Zn2+. It was demonstrated that the accumulated amount of Zn2+ in all sampling experiments with the newly developed PSD was independent of the flow pattern of the sampled SS which was in contrast with results obtained with previously developed dip-in and shielded dip-in passive samplers. The flow-through PSD consists of an acrylic-based 3D-printed flow-through compartment, a glass vessel containing the receiving solution (RS) and a polymer inclusion membrane which acts as a semipermeable barrier separating the RS from a stream of the sampled water (i.e. SS). The PIM was composed of 35 wt% commercial dinonylnaphthalene sulfonic acid (DNNS), 55 wt% poly(vinyl chloride) and 10 wt% 1-tetradecanol. Though in some of the experiments the SS was propelled through the PSD by a conventional peristaltic pump, unsuitable for use in the field, it was demonstrated that the replacement of the peristatic pump with a small battery-driven piezoelectric micro pump was straightforward and did not affect the performance of the PSD. This finding proves the suitability of the newly developed flow-through PSD as a cost effective and portable tool for passive sampling of environmental waters free of flow pattern effects.

    更新日期:2018-08-18
  • Enantioselective analysis of ketoprofen in human saliva by liquid chromatography/tandem mass spectrometry with chiral derivatization
    Microchem. J. (IF 2.746) Pub Date : 2018-08-17
    Xing Jin, Chunbo Zhang, Dongri Jin, Yong-Ill Lee

    The enantioselective analytical method for trace ketoprofen (KET) in human saliva was developed for the first time using liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) combined with a derivatization using a chiral reagent, (S)‑1‑methyl‑4‑(5‑(3‑aminopyrrolidin‑1‑yl)‑2,4‑dinitro‑phenyl)piperazine (APy‑PPZ). The APy‑PPZ derivatization enabled highly sensitive detection (detection limit, 0.5 fmol on column) and complete separation with high resolution (Rs = 4.3) of KET enantiomers. The calibration curves of both KET enantiomers in saliva were linear in the concentration range of 5–500 nM. The developed method showed good analytical performance with relative standard deviations (RSDs) below 2.6% and good accuracy (100.5–105.9%) through intra- and inter-assay and gave a potential for practical application to the quantitative determination of KET in human saliva.

    更新日期:2018-08-18
  • Label-free ultrasensitive determination of EcoRI activity based on terminal deoxynucleotidyl transferase generated G-quadruplexes
    Microchem. J. (IF 2.746) Pub Date : 2018-08-17
    Kaimei Fan, Changkuan Zheng, Yanyan Zhao, Haidi Fu, Baohan Qu, Lihua Lu

    In this study, a label-free ultrasensitive fluorescent biosensor for monitoring of EcoRI activity has been developed based on terminal deoxynucleotidyl transferase (TdT) directed G-quadruplexes formation. Double-stranded DNA is specifically cleaved by EcoRI into single-stranded fragments with the newly generated free 3′-OH terminus. In the condition of the polymerization pool containing 10% dTTP, 40% dATP and 50% dGTP, TdT can elongate the cleaved fragments at their 3′-OH ends to produce G-rich DNA sequences which could subsequently form into G-quadruplexes motif in the aid of K+. The obtained G-quadruplexes structure can be recognized by the typical G-quadruplex-selective probe N-methylporphyrin dipropionate IX (NMM). Thus, EcoRI activity could be easily and sensitively determined by using this detection platform. The detection limit for EcoRI is as low as 0.07 U/mL according to the linear concentration range of 0.1–30 U/mL. Moreover, the proposed assay showed high potential in real sample detection. This detection platform is label-free, highly sensitive, simple to operate and cost effective, possessing high application potential as a useful tool for endonuclease detection. Moreover, we also demonstrated the capability of this strategy to detect EcoRI in serum sample, showing high application potential as a useful tool for endonuclease detection.

    更新日期:2018-08-18
  • Electrochemical behavior of Diosmin and its sensitive determination on ZrO2-NPs-coated poly(diallyldimethylammonium chloride)-functionalized graphene modified electrode
    Microchem. J. (IF 2.746) Pub Date : 2018-08-17
    Huichao Li, Yongqin Liu, Lu Wang, Kai Sheng, Lina Zou, Baoxian Ye

    A new nanocomposite, zirconium dioxide nanoparticles decorated poly(diallyldimethylammonium chloride)-functionalized graphene (ZrO2-PDDA-Gr), was successfully synthesized through a simple and green method. The simultaneous reduction of grapheme oxide (GO) and formation of ZrO2 to produce the ZrO2-PDDA-Gr had been achieved under hydrothermal conditions. The ZrO2-PDDA-Gr showed excellent conductivity and strong adsorption ability toward Diosmin and thus was used to be an excellent probe for electrochemical sensing. The electrochemical characteristics of Diosmin were studied in detail and some dynamics parameters of electrode process were also calculated to discuss the reaction mechanism. Under the optimized conditions, a lower detection limit of 2 × 10−9 mol L−1 (S/N = 3) and a wide linear detection range from 5 × 10−9 to 2 × 10−6 mol L−1 were achieved by differential pulse voltammetry (DPV). Additionally, the proposed electroanalytical methodology was applied in fresh lemon leaves and tablets with satisfactory results, showing that fabricated sensor has potential in application.

    更新日期:2018-08-18
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  • 更新日期:2018-08-17
  • Effect of nature and structure of synthetic anionic food dyes on their sorption onto different sorbents: Peculiarities and prospects
    Microchem. J. (IF 2.746) Pub Date : 2018-08-15
    Tatiana I. Tikhomirova, Gulselem R. Ramazanova, Vladimir V. Apyari

    In this paper, results of a comparative study on sorption of synthetic anionic food dyes onto different sorbents are represented. Five anionic food dyes (3 sulfoazo dyes – E-102, E-110, E-124; a quinophthalone dye – E-104; and a triphenylmethane dye – E-143) and four different sorbents (silica-C16, hypercrosslinked polystyrene, alumina, and polyurethane foam) were examined. Effects of pH, ionic strength were evaluated. Quantitative characteristics of the dye sorption were calculated and effectiveness of different sorbents toward the dyes was assessed. Optical properties of the dyes on the sorbent surface were estimated and compared. Possible mechanisms of the sorption were proposed. Effects of the structure of dyes and the nature of sorbents on efficiency of the sorption were revealed. Based on this study, recommendations regarding sorption isolation and preconcentration of anionic food dyes have been made and a method for direct determination of the dyes by diffuse reflectance spectroscopy on sorbent surface after flow-based preconcentration has been developed.

    更新日期:2018-08-15
  • Effect of alkaline treatment on the fruit peel of Pachira aquatic Aubl.: Physico-chemical evaluation and characterization
    Microchem. J. (IF 2.746) Pub Date : 2018-08-14
    M.S. Carvalho, C.F. Virgens

    Due to their bioavailability, lignocellulosic materials have gained increasing attention, and several chemical treatments been performed to promote modifications in their structure. Alkaline treatment promotes modifications in native cellulose and adds alkaline groups to the surface of the material, potentiating its use as an adsorbent. In this study, the effect of alkaline treatment with 2‑aminopropane (C3H9N 10% m v−1) and sodium hydroxide (NaOH 10% m v−1) on the fruit peel of Pachira aquatic Aubl. was evaluated, generating PBO and PBI samples, respectively. The samples were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electronic microscopy (SEM), thermal analysis, point of zero charge, crystallinity index, moisture content and the alkaline groups were determined using the Boehm's method. The results show that organic alkaline treatment decreased the crystallinity of the material, while the inorganic alkaline treatment added alkaline groups to the surface of the sample.

    更新日期:2018-08-15
  • Quantitative approaches to the determination of elements in lake sediments by total reflection X-ray fluorescence
    Microchem. J. (IF 2.746) Pub Date : 2018-08-14
    Galina V. Pashkova, Tatyana S. Aisueva, Alexandr L. Finkelshtein, Tatyana Yu. Cherkashina, Alexandr A. Shchetnikov

    Element distribution data in lake sediments are widely used to study environmental and climate change over geological time scales. Total reflection X-ray fluorescence (TXRF) seems to be well suited for fast multi-elemental analysis of small quantities of subsamples obtained by cutting a sediment core at different intervals. The TXRF technique based on the direct analysis of a suspension prepared by mixing 20 mg of powdered sample and 2 mL of an aqueous 1% Triton X-100 solution was applied to the various reference materials of sedimentary rocks and samples of lake sediments to determine Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, and Ba contents. It was shown that the element internal standard, as well the Compton scattered peak, can be used to compensate the error associated with the sample deposition process. Different quantitative approaches have been proposed and evaluated using the reference materials of the sedimentary rocks: (i) internal standardization, (ii) external calibration with correction by means of adding an internal standard, (iii) external calibration with the ‘fluorescent-to-Compton’ correction. It was shown that the external calibrations can compensate systematic overestimation or underestimation of the TXRF results obtained using the internal standard method, especially for Al, K, V, Cr, Zn, Rb, and Ba. The TXRF results for Ca, Ti, Mn, Fe, Ni, Cu, and Sr weakly depend on the quantitative procedure.

    更新日期:2018-08-14
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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