Biomonitoring urinary pesticide metabolites in preschool children by supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress.

Investigating pesticide exposure and oxidative stress in preschool children is essential for elucidating the determinants of environmental health in early life, with human biomonitoring of urinary pesticide metabolites serving as a critical strategy for achieving this objective. This study demonstrated biomonitoring of 2 phenoxyacetic acid herbicides, 2 organophosphorus pesticide metabolites, and 4 pyrethroid pesticide metabolites in 159 preschool children and evaluated their association with oxidative stress biomarker 8-hydroxydeoxyguanosine. An enzymatic deconjugation process was used to release urinary pesticide metabolites, which were then extracted and enriched by supported liquid extraction, and quantified by ultra-high performance liquid chromatography-tandem mass spectrometry with internal standard calibration. Dichloromethane: methyl tert­butyl ether (1:1, v/v) was optimized as the solvent for supported liquid extraction, and we validated the method for linear range, recovery, matrix effect and method detection limit. Method detection limit of the pesticide metabolites ranged from 0.01 µg/L to 0.04 µg/L, with satisfactory recoveries ranging from 70.5 % to 95.5 %. 2,4,5-Trichlorophenoxyacetic acid was not detected, whereas the other seven pesticide metabolites were detected with frequencies ranging from 10.1 % to 100 %. The concentration of urinary pesticide metabolites did not significantly differ between boys and girls, with the median concentrations being 9.39 µg/L for boys and 4.90 µg/L for girls, respectively. Spearman correlation analysis indicated that significant positive correlations among urinary metabolites. Bayesian kernel machine regression revealed a significant positive association between urinary pesticide metabolites and 8-hydroxydeoxyguanosine. Para-nitrophenol was the pesticide metabolite that contributed significantly to the elevated level of oxidative stress.

Supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of urinary polycyclic aromatic hydrocarbon metabolites and their application for human biomonitoring.

Polycyclic aromatic hydrocarbons (PAHs) are a class of highly lipophilic and ubiquitous, persistent organic pollutants with carcinogenic and mutagenic toxicities. They are a great public health concern, and avoiding exposure to them is a high priority. Human biomonitoring is critical for the evaluation of exposure levels to PAHs by the general population. In this work, we demonstrated the biomonitoring of eleven hydroxylated PAHs (OHPAHs) in urine samples from 226 volunteers from Guangzhou, and evaluated the health risks. The urinary PAH metabolites were released by enzymatic deconjugation, separated, and enriched by supported liquid extraction, and then quantified by ultra-high performance liquid chromatography-tandem mass spectrometry. The limit of quantification of the individual OHPAHs ranged from 10 ng/L to 40 ng/L, and satisfactory recoveries were obtained, ranging from 92.6% to 97.6%. The detection frequencies of the OHPAHs were 100%, and naphthalene metabolites were found at the highest concentrations with a geometric mean of 8.61 µg/L. The mean total OHPAH level in the urine samples of males (13.2 µg/L) was significantly higher than that of females (5.84 µg/L). Pearson correlation analyses indicated significant and positive correlations among urinary OHPAHs. The total estimated daily intake of PAHs was calculated, and a low health risk was obtained by evaluating their hazard quotients and hazard indexes.

Glycosyl imprinted mesoporous microspheres for the determination of glycopeptide antibiotics using ultra-high performance liquid chromatography coupled with tandem mass spectrometry.

Glycopeptide antibiotics are critical weapons against serious Gram-positive resistant bacteria, and therefore the development of analytical methods for their determination is essential. In this work, with the aim of extending the scope of molecularly imprinted mesoporous materials to the recognition of large molecules such as proteins and peptides, we selected the glycosyl moiety of glycopeptide antibiotics as a template and synthesised a boronic acid functional monomer by click chemistry reaction to prepare glycosyl imprinted mesoporous microspheres. On the basis of boronate affinity, the template and the functional monomer formed a self-assembly structure that was incorporated into the silica framework during polymerisation. The removal of the glycosyl moiety created cavities with boronic acid groups covalently anchored to the pore walls of the glycosyl imprinted mesoporous microspheres. The resultant microspheres showed regular spherical shape, narrow size distribution and porous structure and exhibited high adsorption capability and fast adsorption kinetics. The size exclusion effect of the mesoporous structure prevents large molecules from entering the cavities, while the glycosyl imprinted cavities provide selectivity for glycopeptide antibiotics. The glycosyl imprinted mesoporous microspheres were employed to separate six glycopeptide antibiotics in serum samples, which were then determined using ultra-high performance liquid chromatography tandem mass spectrometry. The proposed method exhibited satisfactory linearity in the range of 0.1 to 20.0 µg/L, demonstrating great potential for the determination of glycopeptide antibiotics in serum samples.

Highly sensitive determination of amanita toxins in biological samples using ß-cyclodextrin collaborated molecularly imprinted polymers coupled with ultra-high performance liquid chromatography tandem mass spectrometry.

In this work, a ß-cyclodextrin functional vinyl monomer was synthesized and the common moiety of five amanita toxins was used as the template for preparing molecularly imprinted polymers (MIPs). Chemical calculation was used to evaluate and describe the binding interactions between the template and the functional monomer. The preparation conditions were optimized and the resultant MIPs were characterized and employed as solid-phase extraction (SPE) sorbents. The SPE conditions including the amount of sorbent, extraction solution, and eluting solution were also optimized for the enrichment of the five toxins. Using an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), detection limits ranging from 0.34-0.42 µg/L, 0.16-0.33 µg/L, and 0.035-0.056 µg/kg were achieved for the five toxins in serum, urine and liver samples, respectively. The proposed method was further applied to the determination of the amanita toxins in suspected samples and showed great potential in the diagnosis of mushroom poisoning.

Ultra-high performance liquid chromatography tandem mass spectrometry for the determination of five glycopeptide antibiotics in food and biological samples using solid-phase extraction.

This paper demonstrated the development and validation of an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of five glycopeptide antibiotics in food and biological samples. The target glycopeptide antibiotics were isolated from the samples by solvent extraction, and the extracts were cleaned with a tandem solid-phase extraction step using mixed strong cation exchange and hydrophilic/lipophilic balance cartridges. Subsequently, the analytes were eluted with different solvents, and then quantified by UHPLC-MS/MS in the positive ionization mode with multiple reaction monitoring. Under optimal conditions, good linear correlations were obtained for the five glycopeptide antibiotics in the concentration range of 1.0 µg/L to 20.0 µg/L, and with linear correlation coefficients >0.998. Employing this method, the target glycopeptide antibiotics in food and biological samples were identified with a recovery of 83.0-102%, and a low quantitation limit of 1.0 µg/kg in food and 2.0 µg/L in biological samples with low matrix effects.