Sulfonamide antibiotics (SAs) are widely used in veterinary medicine but are poorly metabolized in biological systems; thus, they can cause a selective pressure to promote the proliferation of antibiotic resistant pathogens and threaten human health. Persulfate (PS)-based advanced oxidation processes (AOPs) have been applied for SA degradation, but using transition metal ions as PS activators is relatively limited. In this study, sulfamethazine (SMZ) was used as a model SA to evaluate the performance of a Cu 2+ -activated PS system. Cu 2+ -PS exhibited better SMZ removal than other metal ions, and 25 mg/L SMZ can be degraded in the presence of 0.2 mM Cu 2+ and 2.5 g L −1 PS within 120 min. Various anions inhibited SMZ degradation to different degrees except HCO 3 − . Among the cations, Fe 3+ significantly inhibited SMZ removal, while Ni 2+ increased the removal rate. High concentrations of humic acid and protein also increased the degradation rate of SMZ. Radical and singlet oxygen quenching experiments, together with the results of electron spin-resonance spectroscopy (ESR), showed that the main active species generated from Cu 2+ -PS are SO 4 · - and ·OH. The degradation pathway of SMZ was identified through HPLC-HRMS. Direct SO 4 · - and ·OH oxidation products of SMZ were not found, suggesting that the complex formed between Cu 2+ and SMZ may affect the fate of SMZ. On the other hand, the efficiency and selectivity of Cu 2+ -PS against different SAs were confirmed. Overall, this study provides a facile and effective method for SMZ and other SA removal.
For the identification of trace-level organic nitrogen compounds (NCs) in gasoline, a method consisting of water-assisted dispersive solid-phase extraction (DSPE) and high-performance liquid chromatography-high resolution mass spectrometry was developed in which mixed-mode cation exchange was used as the adsorbent. To increase the DSPE efficiency, water was dispersed into the gasoline to increase the pronation of NCs and enhance the ionic interaction with the adsorbent. After systematic optimization of DSPE conditions, including the adsorbent mass, sample volume, water to gasoline ratio, sample loading time, washing and elution solvents, sensitive determination of NCs (detection limits from 0.1 to 5 ng/L for the 14 analytes) was achieved by this method with a 100-fold enrichment. A number of unknown NC isomers were observed from the extracted ion chromatograms based on the accurate determination of mass-to-charge ratio (m/z), from which two sets of isomers at theoretical m/z of 122.09643 and 136.11208 were selected for identification. By careful elucidation of the product ion spectra of the selected ions, 16 NCs were putatively identified, in which six non-aniline homologs were reported for the first time.
危险品化学品经营许可证（带存储）