Molecularly imprinted polymer coupled with dispersive liquid–liquid microextraction and injector port silylation: A novel approach for the determination of 3-phenoxybenzoic acid in complex biological samples using gas chromatography–tandem mass spectrometry

Molecularly imprinted dispersive micro solid-phase extraction coupled with high-performance liquid chromatography for the determination of four aflatoxins in various foods

A new dummy template-based molecularly imprinted dispersive micro solid-phase extraction (MI-d-µSPE) coupled with HPLC-FLD developed for the simultaneous determination of four aflatoxins (B1, B2, G1, G2) in various food matrices. The synthesized MIP was used as a dispersive solid-phase extraction (dSPE) sorbent for aflatoxins extraction. The chemometric approach was used to identify the optimum conditions of dSPE. The results showed the amount of MIP sorbent (55 mg), adsorption time (12.5 min), and %ACN (75%) were significant extraction parameters. The method has a detection limit in the range of 0.059-0.208 µg kg-1 and a quantification limit in the range of 0.197-0.694 µg kg-1 for aflatoxins. The intra- and inter-day precision was less than 5%, and recoveries were 79.1-109.4%. The expanded uncertainty of the developed method was found to be 2.9-22.8%. The new MI-d-µSPE with HPLC-FLD method was applied for 37 food matrices.

Development of nanobody-based flow-through dot ELISA and lateral-flow immunoassay for rapid detection of 3-phenoxybenzoic acid

As a major metabolite of pyrethroid pesticides, 3-phenoxybenzoic acid (3-PBA) can be an indicator of health risk and human exposure assessment. Based on nanobodies (Nbs), we have developed a rapid flow-through dot enzyme linked immunosorbent assay (dot ELISA) and gold nanoparticle (GNP) lateral-flow immunoassay for detecting 3-PBA. The limit of detection (LOD) values for detecting 3-PBA by flow-through dot ELISA and GNP lateral-flow immunoassay were 0.01 ng mL-1 and 0.1 ng mL-1, respectively. The samples (urine and lake water) with and without 3-PBA were detected by both nanobody-based flow-through dot ELISA and GNP lateral-flow immunoassay, as well as liquid chromatography-mass spectrometry (LC-MS) for validation. There was good consistency between the results of the immunoassays. This demonstrated that the two developed nanobody-based immunoassays are suitable for rapid detection of 3-PBA.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

Determination of Urinary PAH Metabolites Using DLLME Hyphenated to Injector Port Silylation and GC-MS-MS

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and well-known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure, and there is a need to measure these metabolites at low concentrations. So, a precise and eco-friendly analytical method has been developed for rapid determination of PAH metabolites. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS-MS) analysis is reported for the analysis of seven urinary PAH metabolites. Factors affecting DLLME and IPS, such as type and volume of extraction and disperser solvent, pH, ionic strength, injector port temperature, volume of N,O-bis(trimethylsilyl)trifluoroacetamide and type of solvent were investigated. Under optimized conditions, the limit of detection and limit of quantification were found to be in the range of 1-9 and 3-29 ng/mL, respectively. Satisfactory recoveries of metabolites in urine samples in the range of 87-95% were found. The developed method has been successfully applied for the determination of PAH metabolites in urine samples of exposed workers. DLLME-auto-IPS-GC-MS-MS method is time, labor, solvent and reagent saving, which can be routinely used for the analysis of urinary PAH metabolites.

Detection of 3-phenoxybenzoic acid in river water with a colloidal gold-based lateral flow immunoassay

3-Phenoxybenzoic acid (3-PBA) is a general metabolite of synthetic pyrethroids. It could be used as a generic biomarker for multiple pyrethroids exposure for human or pyrethroid residues in the environment. In this study, monoclonal antibodies (mAbs) against 3-PBA were developed by using PBA-bovine serum albumin (BSA) as an immunogen. In the competitive enzyme-linked immunosorbent assay (ELISA) format, the I50 and I10 values of purified mAbs were 0.63 and 0.13 μg/ml, respectively, with a dynamic range between 0.19 and 2.04 μg/ml. Then, the colloidal gold (CG)-based lateral flow immunoassay was established based on the mAbs. The working concentration of coating antigen and CG-labeled antibodies and the blocking effects were investigated to get optimal assay performance. The cutoff value for the assay was 1 μg/ml 3-PBA, and the detection time was within 10 min. A total of 40 river water samples were spiked with 3-PBA at different levels and determined by the lateral flow immunoassay without any sample pretreatments. The negative false rate was 2.5%, and no positive false results were observed at these levels. This lateral flow immunoassay has the potential to be an on-site screening method for monitoring 3-PBA or pyrethroid residues in environmental samples.

High performance liquid chromatography: Tandem mass spectrometric determination of cisplatin levels in different visceral pleura layers of rats

The aim of the present study was to investigate the concentration of cisplatin in different layers of the visceral pleura in rats, following drug administration. In this study, a sensitive and specific liquid chromatography method coupled with electrospray ionization-tandem mass spectrometry was established to investigate the disposition of cisplatin in different layers of the visceral pleura in rats. Methodological data, including specificity, linearity, accuracy, recovery, precision and lower limits of quantification, confirmed that this novel method may be used to efficiently quantify the cisplatin concentrations in visceral pleura of rats following administration of the drug. Furthermore, the results demonstrated that the desired drug concentration was not achieved in the outer or inner elastic layers of the visceral pleura following injection with cisplatin through various administration methods.