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Here, an imine‐linked‐based spherical covalent organic framework (COF) was prepared at room temperature. The as‐synthesized spherical COF served as an adsorbent in dispersive solid‐phase extraction (dSPE), by its virtue of great surface area (1542.68 m2/g), regular distribution of pore size (2.95 nm), and excellent stability. Therefore, a simple and high‐efficiency dispersive solid phase extraction method based on a spherical COF coupled with high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS) was established to determine aryl organophosphate esters in biological samples. This approach displayed favorable linearity in the range of 10.0–1000.0 ng/L (r > 0.9989), a high signal enhancement factor (58.8–181.8 folds) with low limits of detection (0.3–3.3 ng/L). Moreover, it could effectively eliminate complex matrix interference to accurately extract seven aryl organophosphate esters from mouse serum and tissue samples with spiked recoveries of 82.0%–117.4%. The as‐synthesized spherical COF has been successfully applied in sample preparation. The dSPE‐HPLC‐MS/MS method based on a spherical COF has potential application to study the pollutants' metabolism in vivo. [ABSTRACT FROM AUTHOR]

A novel vortex-assisted dispersive liquid–liquid microextraction method based on deep eutectic solvent (VA–DLLME–DES) completed in syringe has been established to extract 12 quinolones from honey. This method is an improvement of traditional DLLME. In this work, the green DES prepared with heptanoic acid and thymol was used for extractant rather than traditional organic extraction solvent. Without centrifugation, the phases were separated in the way of removing aqueous phase by pushing the syringe and extractant phase was collected for ultra performance liquid chromatography-mass spectrometry (UPLC–MS) analysis. The stability of DES and some experimental parameters (type, molar ratios and volume of extraction solvent, type and volume of dispersant, vortex time and effect of pH and NaCl) were evaluated. In the range of 2–100 ng/mL, the proposed method showed good linearities (r2 ranged from 0.996 to 0.999). The extraction recoveries were obtained in the range of 75.01%–117.05% and relative standard deviations were less than 13.83% for inter- (n = 6) and intra-day (n = 3) precisions. The limits of detection and quantification were 3 ng g−1 and 10 ng g−1, respectively. The developed method with the advantages of simple operation, short extraction time and less consumption organic solvent provides a technical idea for green, simple and time-saving sample preparation methods. [ABSTRACT FROM AUTHOR]

A magnetic nanoparticle (MNP)-based lateral flow immunochromatography assay (LFIA) was established to detect fluoroquinolones (FQs) in milk. This method is an improvement of traditional Au nanoparticle (AuNP)-based LFIA. Compared with AuNP-labeled antibody, the combination between MNPs and antibody is stronger and more stable, and the preparation process is convenient. In this study, the color intensity of MNPs-LFIA test strip was analyzed, which laid a research foundation for magnetic quantitative analysis and high sensitivity analysis of LFIA. The limits of detection (LODs) for 10 FQs in phosphate buffer (PB) solution ranged from 1 to 5 ng/mL, and in milk ranged from 2 to 20 ng/mL. The recovery in spiked milk sample ranged from 16.47 to 83.67%. The log functions of analyte concentration and T/C value were fitted into a linear equation. The specificity of the MNPs-LFIA is satisfactory, without cross-reaction with antibiotics from other chemical classes. The results of this method are consistent with those of ultra-performance liquid chromatography-mass spectrometry, indicating the MNPs-LFIA method is reliable and accurate. As far as we know, this is the first time that MNPs-LIFA has been applied to the detection of FQs in milk. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sensitive and reliable SPE-LC-MS/MS method was developed for estrogen determination. • The limits of detection (LODs) for six estrogenic compounds were between 2.5 and 19.2 ng/L. • The effects of matrix background on determination were evaluated and interpreted. • Both matrix suppression and enhancement were observed in environmental samples. • There was a positive correlation between LODs and TOC in various water matrices. An analytical method has been developed and validated for the determination of six estrogens and estrogen mimics, namely estriol (E3), bisphenol A (BPA), 17β-estradiol (E2), estrone (E1), ethynyl estradiol (EE2) and dienestrol (DIE), with frequent occurrence in the natural environment. Solid phase extraction coupled with liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) using electrospray ionization (ESI) in a negative mode was applied to concentration, identification, and quantification of estrogens and estrogen mimics. The SPE conditions were optimized as the selection of C18 as cartridges and MeOH as an eluent, and the control of solution pH at 9.0. The method was validated by satisfactory recoveries (80–130%) and intra-day and inter-day precision (<18.4%, as relative standard deviation), and excellent linearity for calibration curves (R2 > 0.996). The limits of detection (LODs) for six target estrogenic compounds ranged between 2.5 and 19.2 ng/L. The effects of matrix background on the determination were evaluated in terms of LODs, LOQs, analyte recovery, and slopes of calibration curves in five different water matrices. Matrix effects by tap water were negligible. However, both matrix suppression and enhancement (i.e., E3, E1, DIE) were observed in surface water and wastewater. The positive correlation between LODs and TOC in various water matrices indicated the negative effect of organic pollutants on the method sensitivity. The sum of target estrogenic compounds in environmental samples were within 17–9462 ng/L. [ABSTRACT FROM AUTHOR]