The effect of adding organosilicon and mineral oil adjuvants after being applied to the residues of difenoconazole and propiconazole in banana leaves was studied. The partition of the pesticides between soil, leaves and fruits was evaluated.

Two enantiomers of glufosinate were separated under reverse-phase conditions on a chiral crown stationary phase (CROWNPAK CR­(+)). An efficient and reliable chiral analytical method was developed to determine the glufosinate enantiomers and two metabolites in soil and water samples using high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). The linearities of the matrix-matched calibration curves in five water and four soil samples were good with a correlation coefficient R 2 > 0.998, and the mean recoveries were 85.2–100.4%, with relative standard deviations of 1.0–7.1%. l-Glufosinate was degraded faster than d-glufosinate in four nonsterile natural soil and two nonsterile natural water samples. The degradation half-lives of the enantiomers ranged from 3.4 to 33.0 days in the soil samples, but glufosinate was stable in the five water samples, less than 22% of the applied substance degraded at the end of the experiment (100 days). Degradation in sterile soil was not enantioselective. The two enantiomers were configurationally stable in the four soil and five water samples. In most cases of glufosinate degradation in soils, the percentage of 3-methylphosphinicopropionic in relation to the parent was higher than that of N-acetyl-glufosinate. l-Glufosinate was preferentially degraded in the four soils, and formation of 3-methylphosphinicopropionic acid and N-acetyl-glufosinate was enantiomer dependent.

The present study investigates the occurrence of pymetrozine residues in cauliflower samples obtained from six cauliflower‐producing areas of China during fixed time periods in 2017 and estimates the dietary risk of pymetrozine in cauliflower. A liquid chromatography with tandem mass spectrometry method was developed and validated to detect pymetrozine in cauliflower. The samples were extracted using 20 mL of acetonitrile and purified with dispersive solid‐phase extraction using C18 as sorbent. The limit of quantification of pymetrozine was 0.008 mg/kg in cauliflower. The recoveries of the analyte were 82.04–95.18% with RSD <8.45%. The calibration curves for pymetrozine showed good linearities in the concentration range 0.004–2.0 mg/L with determination coefficients (R2) >0.999. Pymetrozine dissipated rapidly in cauliflower with a half‐life of <4 days. The terminal residues of pymetrozine were <0.008–0.0881 mg/kg in cauliflower at 7, 10 and 14 days after spraying from six sites. The routine washing process removed about half amount of the pymetrozine in cauliflower; the reduction ratios were 51.0–52.8%. The dietary risk assessment indicated that pymetrozine did not exhibit obvious dietary health risks in cauliflower when good agricultural practices were implemented.