Anwei Chen,Wenjie Li,Xiaoxiao Zhang,Cui Shang,Si Luo,Ruoyu Cao,Doudou Jin
The extensive use of neonicotinoid pesticides in the past two decades caused serious impacts on many kinds of living beings. Therefore, it has been strongly suggested to detoxify and eliminate neonicotinoids’ residual levels in environment. Here, the degradation and detoxification of thiamethoxam (THX) by white-rot fungus Phanerochaete chrysosporium was conducted. Results shown that P. chrysosporium can tolerate THX and degraded 49% of THX after incubation for 15 days, and then 98% for 25 days at the initial concentration of 10 mg/L, which indicates the excellent degradation ability of this fungus to THX. Based on the by-products identified, THX underwent dechlorination , nitrate reduction , and C–N cleavage between the 2-chlorothiazole ring and oxadiazine. ( Z )-N-(3-methyl-1,3,5-oxadiazinan-4-ylidene)nitramide and 3-methyl-1,3,5-oxadiazinan-4-imine were identified as the main metabolites. The impacts of THX and its corresponding degradation intermediates on the growth of E. coil and Microcystis aeruginosa as well as the germination of rape and cabbage demonstrated that P . chrysosporium effectively degrades THX into metabolites and reduces its biotoxicity. The present work demonstrates that P . chrysosporium can be effectively used for degradation and detoxification of THX.
Xianjiang Li,Wei Zhang,Shukun Zhou,Xiao Li,Mengling Tu,Yunxiao Zhu,Qinghe Zhang,Hongmei Li
Thiamethoxam (TMX) belongs to the second-generation neonicotinoid pesticide, which is among the most common residual in food commodities. To guarantee accurate quantification and traceability of results in food samples, certified reference materials (CRMs) are indispensable benchmark. TMX was characterized and its purity value was assessed by two independent measurement methods including mass balance (MB) and quantitative nuclear magnetic resonance spectroscopy (qNMR). Its mass fraction was 997.0 mg/g and 991.7 mg/g in MB and qNMR, respectively. Eventually, a purity of 994 mg/g with standard uncertainty of 3 mg/g ( k = 2) was assigned to TMX.
The solubility and thermodynamic properties of thiamethoxam in six monosolvents [acetone, dichloromethane, dimethylformamide (DMF), methyl acetate, ethyl acetate, and 1-methyl-2-pyrrolidinone (NMP)] and two binary solvents (DMF + ethyl acetate and NMP + ethyl acetate) were reported. Solubility determinations were performed through the laser monitoring method at T = (278.15–323.15) K and p = 0.1 MPa (except for dichloromethane at 273.15–313.15 K). The measurement results demonstrated that the solubility of thiamethoxam in all of the six monosolvents and two binary solvents shows a positive relationship with temperature variation, and with the mass fraction of positive solvents (DMF, NMP) in the binary mixed solvents increasing, the solubility of thiamethoxam also increases. Then, the recorded solubility of thiamethoxam in all monosolvents was regressed by λh, modified Apelblat, two-suffix Margules, NRTL, and UNIQUAC models, while the solubility of thiamethoxam in two binary solvents was regressed by λh, modified Apelblat, three-suffix Margules, NRTL, and UNIQUAC models. Furthermore, by calculating the deviation between the experimental data and the regression data, it shows that the modified Apelblat model can provide more accurate correlation results for the solubility of thiamethoxam in all of the solvents studied.
危险品化学品经营许可证（带存储）