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Pergamon Press
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Pergamon Press

0039-9140

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    Towards electrochemical surface plasmon resonance sensor based on the molecularly imprinted polypyrrole for glyphosate sensing

    Ramanavicius A.Ramanaviciene A.Balciunas D.Plausinaitis D....
    5页
    查看更多>>摘要:? 2022In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an electrochemical surface plasmon resonance (ESPR) sensor. The results described in this study disclose some restrictions and challenges, which arise during the development of glyphosate ESPR sensor based on the molecularly imprinted polymer development stage. It was demonstrated, that glyphosate could significantly affect the electrochemical deposition process of molecularly imprinted polymer on the electrode. The results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and surface plasmon resonance (SPR) have demonstrated that glyphosate molecules tend to interact with bare gold electrode and thus hinder the polypyrrole deposition. As a possible solution, the formation of a self-assembled monolayer (SAM) of 11-(1H-Pyrrol-1-yl)undecane-1-thiol (PUT) before electrochemical deposition of MIPpy and NIPpy was applied. Dissociation constant (KD) and free energy of Gibbs (ΔG0) values of glyphosate on MIPpy and Ppy without glyphosate imprints (NIPpy) were calculated. For the interaction of glyphosate with MIPpy the KD was determined as 38.18 ± 2.33?10?5 and ΔG0 as ?19.51 ± 0.15 kJ/mol.

    Development and validation of a UHPLC-HRMS-QTOF method for the detection of 132 New Psychoactive Substances and synthetic opioids, including fentanyl, in Dried Blood Spots

    Massano M.Incardona C.Alladio E.Salomone A....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.Dried Blood Spots (DBS) represents a promising micro-sampling technique in the field of forensic toxicology to carry out minimally invasive blood sample collection. In DBS, cheap, fast and easy sampling is combined with effortless store and transport. These properties aimed us to develop and validate a quick and easy procedure for the detection of a large and diverse range of emerging and alarming New Psychoactive Substances (NPS). A drop of whole blood sample was collected on a DBS card and dried for 3 h, from which a total of 132 analytes (including NPS, synthetic opioids NSO and metabolites) plus 13 deuterated internal standards could be extracted using 500 μL of a methanol/acetonitrile mixture (3:1, v/v) and subsequently separated and identified by means of ultra-high-performance liquid-chromatography (UHPLC) coupled to high resolution mass spectrometry (HRMS). The extraction efficiency proved to be reproducible with yields ranging from 30% to 100% depending on the different classes of drugs. Trueness, repeatability, and intermediate precision fulfilled acceptance criteria for almost all synthetic opioids, cathinones and hallucinogens (bias and CV% below ±20%); in particular, the aggregate inter-day trueness data showed extremely limited deviation from the expected concentrations (?10% < bias% < +10%) for 114 target analytes out of 132. The calculated limits of detection ranged from 1.3 to 6.3 ng/mL, consistently exceeding the values experimentally tested. Moderate ion suppression was observed for most analytes, partly caused by blood fortification itself. Good stability of the target analytes at ?20 °C, 4 °C, and 35 °C on DBS cards after drying was observed, even for long periods of time. Optimal storage condition appeared to be at 4 °C resulting in virtually no drugs degradation for up to 40 days. The novel analytical method based on DBS sampling, verified on venous whole blood real samples previously tested positive with our routine procedure, conveys remarkable potential in analytical toxicology, clinical analysis, and doping control.

    Detection and discrimination of antibiotics in food samples using a microfluidic paper-based optical tongue

    Taghizadeh-Behbahani M.Shamsipur M.Hemmateenejad B.
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.Antibiotics are used largely in agriculture and animal farming. As a result, antibiotic residues are found in food products as well as pharmaceutical industries and farming wastes. Since consumption of food products contaminated with antibiotic in excessive residuals causes severe environmental risks, our study here aims to detect the residues level of selected antibiotics in milk and egg. For monitoring of the antibiotic residues in various food diaries, low-cost, simple and rapid methods are required. This paper reports fabricating a disposable microfluidic paper-based analytical device for detection and discrimination of 8 antibiotics. This small but efficient device works based on combination of paper microfluidics, sensor array concept (an array of metallochromic complexes, which provides an optical tongue, and chemometrics data analysis. The discrimination is based on differential interaction of the antibiotics with 5 metal-indicator complexes and displacing the chromogenic indicators. This resulted in specific color changes for each antibiotic. The discriminant models obtained by employing linear discriminant analysis could discriminate antibiotics in real samples of milk and egg white and yolk at concentrations of as low as 5.0 mg L?1 with 100% accuracy. Also, semi-quantitative analysis was provided to detect trace amounts of the antibiotics (1.0 mg L?1).

    Microwave-assisted extraction and gas chromatographic determination of thirty priority micropollutants in biowaste fraction derived from municipal solid waste for material recovery in the circular-economy approach

    Ingrando I.Rivoira L.Castiglioni M.Bruzzoniti M.C....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.European and national waste directives prioritize recycling of wastes, as well as material and energy recovery from wastes themselves. Bio-waste fraction can be converted into new resources whose quality is strictly dependent upon that of waste feedstock. Methods to evaluate the contamination from organic micropollutants in bio-waste are rarely investigated. The aim of this work was to develop an innovative analytical method for the extraction and quantification of 16 polycyclic aromatic hydrocarbons (PAHs) and 14 polychlorinated biphenyls (PCBs, including dioxin-like compounds) in bio-waste. Through a full-factorial experimental design, a microwave-assisted extraction technique was optimized to extract the thirty targeted micropollutants, studying the effect of cyclohexane and dichloromethane as extraction solvents with or without acetone, and of extraction temperature. Purification of the extract was obtained by a silica-based solid-phase extraction cartridge, followed by a sulfuric acid treatment. The analysis was carried out by gas chromatography coupled with mass spectrometry. The optimized method, validated directly in the bio-waste matrix fortified with isotopically marked surrogates, is characterized by good extraction recoveries, included within 47 and 106% (relative standard deviations <10%), by satisfactory intra-day (<1.1%) and inter-day (<9.3%) precision, and by low matrix effect (<17%), despite the complexity of the matrix. The optimized procedure, applied to the analysis of PAHs and PCBs in a bio-waste sample collected from a local anaerobic digestion and composting plant, showed a total PAHs content of 562 μg/kg. As regards PCBs, the dioxin-like congener PCB 118 was the only compound quantified (25 ± 6 μg kg?1).

    An efficient glucose sensor thermally calcined from copper-organic coordination cages

    Wei L.Ding J.Wu J.Li L....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.Due to the harmfulness of diabetes, a fast and efficient glucose detector is particularly important. Metal-organic polyhedron (MOP) provides a porous framework and a special matrix, which makes it an excellent precursor for electrochemical detection. Herein, we report a novel MOP as a precursor for the preparation of an electrocatalytic detector for glucose. The new metal-organic polyhedron of Cu4(TPDC)4 can be solvothermally obtained and characterized by X-ray crystallography, which can be thermally converted into nanosized copper oxides embedded into graphitic carbon layers (MOP-CO). The as-prepared MOP-CO electrode is further applied to glucose detection, which shows a fast response time (<1 s) in a wide linear range of 0–4000 μM and high sensitivity of 2720 μA mM?1 cm?2, as well as low detection limit (26 nM (S/N = 3)), good anti-interference, repeatability and stability (>3600 s).

    Assessment of automated off-line solid-phase extraction LC-MS/MS to monitor EPA priority endocrine disruptors in tap water, surface water, and wastewater

    Goeury K.Vo Duy S.Sauve S.Prevost M....
    5页
    查看更多>>摘要:? 2022EPA method 539.1 recently introduced an expanded list of priority endocrine-disrupting compounds (EDCs), some of which were also included in the Unregulated Contaminant Monitoring Rule 3 (UCMR3). Though standardized methods are available for drinking water, analysis of steroid hormones and bisphenol A (BPA) at the ultra-trace level remains challenging. This study set out to evaluate the suitability of automated off-line solid-phase extraction (SPE) liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for the determination of EPA-priority EDCs in environmental water matrixes (tap water, surface water, and wastewater influents and effluents). The target molecules included 14 steroid hormones (altrenogest, androstenedione, equilenin, equilin, α-estradiol, β-estradiol, estriol, estrone, ethinylestradiol, levonorgestrel, medroxyprogesterone, norethindrone, progesterone, testosterone) and BPA. Factors that may influence the analytical performance were assessed. This involved, for instance, testing combinations of SPE materials from different brands and protocol variations. Several materials presented absolute extraction efficiencies in acceptable ranges. Initial sample pH, nature of reconstitution medium, and mobile phase salt concentration were among the potential factors affecting analyte signal. Storage conditions (different preservative agents) possibly exerted the strongest influence, in agreement with the literature. Limits of detection were in the range of 0.03–0.5 ng/L in drinking water, 0.1–0.5 ng/L in surface water, and 0.16–1 ng/L in wastewater. Method validation also involved testing linearity, accuracy, and precision in reagent water and matrix-matched extracted calibrants. The method was applied to field-collected water samples in Eastern Canada. Summed EDC concentrations remained low in tap water (<LOQ–0.92 ng/L), while higher detection frequencies and contamination levels were reported in riverine surface waters (2.6–37 ng/L) and municipal wastewaters (10–424 ng/L).

    Exploring multifunctional behaviour of g-C3N4 decorated BiVO4/Ag2CO3 hierarchical nanocomposite for simultaneous electrochemical detection of two nitroaromatic compounds and water splitting applications

    Shafi A.Bano S.Sabir S.Khan M.Z....
    5页
    查看更多>>摘要:? 2022Development of multifunctional ternary nanocomposite based electrocatalysts for detection of toxic elements and generation of renewable energy describes an environmentally sustainable technique to address the dual challenges of pollution and energy. Herein, we adopted microwave-assisted synthesis to design a multifunctional graphitic carbon nitride (g-C3N4) decorated BiVO4/Ag2CO3 (BVG@C) hierarchical ternary nanocomposite for sensing and water splitting applications. The morphological, structural and elemental characterizations demonstrate the successful decoration of carbon nitride on the composite surface. The electrochemical activity of BVG@C modified glassy carbon electrode reveals excellent redox behaviour towards simultaneous detection of 4-Nitrophenol (4-NP) and 4-Nitroaniline (PNA). The modified electrode shows rapid amperometric current response with high sensitivity of 2.368 μA mM cm?2 and 1.534 mA mM cm?2 and low detection limit of 0.012 μmol L?1and 0.028 μmol L?1, respectively for 4-NP and PNA. Moreover, the modified electrode was further investigated for hydrogen evolution and oxygen evolution reactions and the electrocatalytic results show admirable activity and good stability for oxygen evolution with very low overpotential of 136 mV in alkaline medium. It is worthwhile to mention that the excellent activity of electrocatalyst can be ascribed to the decoration and electronic interaction of g-C3N4 with the BiVO4/Ag2CO3 nanocomposite, increasing its surface area, active sites, charge transfer and decreasing resistance.

    Characterization of a novel affinity binding ligand for tyrosine nitrated peptides from a phage-displayed peptide library

    Zhang P.Liang S.Wang Y.Chen P....
    5页
    查看更多>>摘要:? 2022As an important post-translational modification in response to oxidative and nitrosative stress, protein tyrosine nitration is deeply involved in many physiological and pathological processes. Identifying tyrosine nitration in proteins is challenging due to its low abundance.Consequently, pre-separation and enrichment of tyrosine-nitrated peptides (TNPs) are necessary before submitting them to mass spectrometry analysis. However, the most popularly used anti-nitrotyrosine antibody pull-down method showed limitations like sequence preference and unspecific binding. Therefore, developing novel affinity purification materials for TNPs is of significance. In the present study, we screened the phage-displayed 12-mer randomized peptide library for affinity binding peptide of the synthetic standard TNP (sTNP, sequence: H2N-GGGGY*GGG-COOH) and identified a peptide named NT-1 (H2N-TLWPFDLWLKTR-COOH) as a promising candidate. NT-1 at extremely low concentration (3 nM) in solutions could be efficiently captured by immobilized sTNP as determined by pull-down and subsequent MALDI-TOF MS analysis. Surface plasmon resonance (SPR) measurement confirmed that NT-1 possesseed a good selectivity, showing more than 100-fold higher binding affinity with TNP than its non-nitrated counterpart. Moreover, NT-1 could efficiently capture various types of TNPs in solutions even in the presence of 1000-fold excessive amount of trypsinized BSA fragments. Most importantly, NT-1 showed superiority to commercially used nitrotyrosine antibody as the former captured more TNPs, with less sequence preference. In summary, our study provided NT-1 as a novel affinity binding ligand for TNPs and should be useful in developing an alternative enrichment strategy for TNPs.

    Sequential combination of solid-phase sorbents to enhance the selectivity of organosulfur compounds for flavour analysis

    Yeam C.W.Huang Y.Goh R.M.V.Ee K.-H....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.Flavour analysis remains challenging due to the range of selectivity demands, from the extraction of multiclass volatile compounds to the purification of low-concentration odourants (e.g. organosulfur compounds) amidst the high food matrix noise. In this study, the varying selectivities of solid-phase extraction (SPE) were leveraged upon for both multiclass and organosulfur compound analysis, using coffee as a model matrix. Polymeric SPE (Bond Elut ENV) was screened for significant (p < 0.05) parameters affecting the recovery of 37 multiclass compounds, and the most influential parameters were optimised using a Box-Behnken design (elution solvent of 67:33 dichloromethane:ethyl acetate, loading pH of 4.8, and wash solvent of water). Following this, low-concentration organosulfur compounds which were challenging to detect in the complex coffee matrix were purified by adding a sequential SPE step for selectivity. A silver-based ligand-exchange SPE step (MetaSEP IC-Ag) was optimised for organosulfur compound recovery (wash solvents of dichloromethane and 43% acetonitrile in dichloromethane, elution solvent of 90 mmol/L 1,4-dithiothreitol in dichloromethane). This was found to be complementary to polymeric SPE's matrix clean-up effect (which improved average organosulfur compound recovery by 5.45 times). Finally, both multiclass and sequential organosulfur extraction techniques demonstrated good performance in terms of reproducibility (1.0–9.0%) and linearity (R2 > 0.995), allowing for the detection of 3-mercapto-3-methylbutyl formate (3.741 ± 0.387 ng/mL) in coffee samples. In conclusion, this study highlights the potential for SPE to address a variety of complex flavour analysis demands with the appropriate selection and combination of solid-phases.

    A facile one-pot synthesis of magnetic iron oxide nanoparticles embed N-doped graphene modified magnetic screen printed electrode for electrochemical sensing of chloramphenicol and diethylstilbestrol

    Pakapongpan S.Tuantranont A.Poo-arporn Y.Poo-arporn R.P....
    5页
    查看更多>>摘要:? 2021Trace determination of antibacterial agents is crucial to minimize risks of human intoxication and in the prevention of serious environmental impacts. Herein, a simple one-pot solvothermal synthesis approach for a magnetic iron oxide embed nitrogen-doped graphene (MIO@NG) nanohybrid was fabricated without the addition of any extra reductant and its application towards ultrasensitive chloramphenicol (CAP) and diethylstilbestrol (DES) electrochemical sensor is demonstrated to screen for antibiotic residue contamination in milk samples. The prepared nanohybrid was modified on a magnetic screen-printed electrode (MSPE) to make it portable for on-site detection. The determination of two additive drugs, CAP and DES, was achieved based on the reduction current response at MIO@NG modified MSPE (MIO@NG/MSPE) to eliminate interference as far as possible. Uniform dispersed MIO nanoparticles are grown in situ on the surface of nitrogen-doped graphene sheets. The morphology of MIO@NG was confirmed by transmission electron microscopy (TEM) analysis. The chemical structure of the prepared MIO@NG was characterized by x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS), Raman spectroscopy, and extended x-ray absorption fine structure (EXAFS). Moreover, the superparamagnism property was investigated by vibrating sample magnetometry (VSM). The electrochemical properties of MIO@NG were evaluated with cyclic voltammetry (CV) and square wave voltammetry (SWV). Sensor performance was evaluated by testing the electrochemical activity of CAP and DES in the presence of interferences. The MIO@NG modified electrode presented superior electrochemical performance, including high sensitivity, high catalytic activity, ultimate sensitivity, very fast detection, selectivity, and excellent performance. The MIO@NG modified electrode demonstrated a detection limit of 10 nM for the detection of CAP and 6.5 nM for DES with satisfactory recovery in real samples.