Studies often neglect the different trends between enantiomers in soil chiral contaminants. In the present study, paclobutrazol was chosen as the target analyte and the selective degradation patterns of this chiral pesticide were investigated in soils. After 14 days of culture, the degradation kinetics results demonstrated the degradation process of the two enantiomers conforms to first-order degradation kinetics equation, and the degradation rates were significantly different (paired t-test, P < 0.05). The degradation rate of (2S,3S)-paclobutrazol (S-paclobutrazol) was higher than that of (2R,3R)-paclobutrazol (R-paclobutrazol), with the concentration decrease of 42.6 and 28.7%, respectively. Meanwhile, the enantiomer fraction (EF) was 0.43 at final sampling point, and the half-life (t1/2) of S-paclobutrazol and R-paclobutrazol were 17.3 and 28.9 days, which demonstrated significant enantioselective degradation. Results from this study served to enhance our understanding about the enantioselective degradation behaviors of chiral pesticides, which provided some scientific basis for the potential risk assessment of chiral pesticides in the environment.

In this study, a novel deep eutectic solvent (DES) containing choline chloride and ethylene glycol was synthesized, and the magnetic polydopamine (PDA) was modified with this deep eutectic solvent to form Fe3O4@PDA-DES. Fourier transformed infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer were used to characterize the proposed adsorbent. Then, this magnetic material was used as an adsorbent in the magnetic solid phase extraction process for the extraction of four sulfonylurea herbicides in water samples. The main parameters relevant to this method were investigated. Under the optimum conditions, the linearity was obtained by five points in the concentration range of 1.0-200 µg L-1 and with the correlation coefficients (r) ≥ 0.9927. The enrichment factors were in a range of 495 to 615 and the relative standard deviations were less than 4.3%. The limits of detection varied from 0.0092 to 0.0113 µg L-1. The recoveries of environmental water samples were 61.9 to 100.1%, and the recoveries of drinking water samples were 71.1-101.9%. All results highlighted the excellent potential of magnetic solid phase extraction coupled with ultra-high performance liquid chromatography strategy in selective separation and extraction of sulfonylurea herbicides in water samples.