A novel method based on solid phase extraction and liquid chromatography-tandem mass spectrometry warrants occurrence of trace xanthates in water.

Huge volumes of wastewater containing organic flotation reagents such as xanthates have been released into the environment via mining activities, greatly threatening the eco-environment safety. A simple and fast method is urgently needed for accurate analysis of various xanthates in mining and environmental water. Here, a robust method is realized for simultaneous determination of three trace xanthates (i.e., potassium ethyl xanthate, potassium butyl xanthate, and potassium isopropyl xanthate) in environmental water samples, including eutrophic water and flotation wastewater using solid phase extraction (SPE) and HPLC-MS/MS. HPLC-MS/MS parameters, SPE cartridges and eluting solvents, pH values, and SPE procedures were optimized. The new method had an excellent linearity in the range of 1-1000 µg/L (R2 ≥ 0.998), low limits of detection (0.02-0.68 µg/L), and satisfactory accuracy and precision (72.9%-107.6% of average recoveries and <5% of relative standard deviations at 1, 10, 50, and 500 µg/L of xanthates). This is a first method developed for determination of trace xanthates in water samples. It was successfully applied to determine the target analytes in outdated flotation wastewater and river water samples, warranting the occurrence of trace xanthates (0.13-16.9 µg/L) in water and necessity of systematic investigation on environmental fate and risk of xanthates.

Interactions between Extracellular DNA and Perfluoroalkyl Acids (PFAAs) Decrease the Bioavailability of PFAAs in Pakchoi (Brassica chinensis L.).

Perfluoroalkyl acids (PFAAs) are emerging ionic organic pollutants worldwide. Great amounts of extracellular DNA (∼mg/kg) coexist with PFAAs in the environment. However, PFAA-DNA interactions and effects of such interactions have not been well studied. Herein, we used isothermal titration calorimetry (ITC), spectroscopy, and computational simulations to investigate the PFAA-DNA interactions. ITC assays showed that specific binding affinities of PFHxA-DNA, PFOA-DNA, PFNA-DNA, and PFOS-DNA were 5.14 × 105, 3.29 × 105, 1.99 × 105, and 2.18 × 104 L/mol, respectively, which were about 1-2 orders of magnitude stronger than those of PFAAs with human serum albumin. Spectral analysis suggested interactions of PFAAs with adenine (A), cytosine (C), guanine (G), and thymine (T), among which grooves associated with thymine were the major binding sites. Molecular dynamics simulations and quantum chemical calculations suggested that hydrogen bonds and van der Waals forces were the main interaction forces. Such a PFAA-DNA binding decreased the bioavailability of PFAAs in plant seedlings. The findings will help to improve the current understanding of the interaction between PFAAs and biomacromolecules, as well as how such interactions affect the bioavailability of PFAAs.

Effects of HLEC on the secreted proteins of epithelial ovarian cancer cells prone to metastasize to lymph nodes.

OBJECTIVE: To study explores the effect of HLEC on the secreted proteins of epithelial ovarian cancer (EOC) cells (SKOV3-PM4) with directional highly lymphatic metastasis. METHODS: Supernatants of four groups of cultured cells, namely, SKOV3 (A), SKOV3+HLEC (B), SKOV3-PM4 (C), SKOV3-PM4+HLEC (D), were collected, and their proteins were detected by antibody arrays and iTRAQ-2D-LC-MALDI-TOF/TOF/MS. Significantly differential proteins were further analyzed via bioinformatics and validated in human serums and cell media via ELISA. RESULTS: Results of antibody arrays and mass spectrometry demonstrated that GRN and VEGFA were upregulated in group C (compared with group A), whereas IGFBP7 and SPARC were downregulated in group D (compared with group C). Comprehensive bioinformatics analysis results showed that IGFBP7 and VEGFA were closely linked to each other. Further validation with serums showed statistical significance in VEGFA and IGFBP7 levels among groups of patients with ovarian cancers, benign tumors, and control groups. Two proteins were upegulated in the first group. VEGFA in the control group was downregulated. For IGFBP, upregulation in the control group and down-regulation in the first group were also observed. CONCLUSION: The HLEC microenvironment is closely associated with directional metastasis to lymph nodes and with differential proteins including cell stromal proteins and adhesion factors. The upregulation of VEGFA and GRN and the downregulation of SPARC and IGFBP7 are closely associated with directional metastasis to lymph nodes in EOC cells.