A novel β-cyclodextrin-based chiral stationary phase for enantioseparation and evaluation of paclobutrazol enantioselective degradation and bioaccumulation in a soil-earthworm system.

A novel cyclodextrin-derived chiral stationary phase (CMHDC) was synthesized by coupling 3-chloro-4-methylphenylcarbamate-mono-6-hexamethylenediamine-β-cyclodextrin to the surface of silica gel via a urea linkage, and was then packed into a column. The chiral separation capability of the CMHDC column was evaluated, and molecular docking was used to explore the chiral recognition mechanism. The column showed good chiral recognition ability for various drugs. The separation mechanism likely depended on differences in hydrogen bonding, hydrophobic interactions, and host-guest inclusion effects. Based on this, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the enantioselective determination of paclobutrazol enantiomers in soil and earthworm samples was developed and validated. The method demonstrated good specificity, and both enantiomers exhibited excellent linearity in the concentration range of 0.025-25.0 μg/mL (r ≥ 0.9972). The accuracy expressed as relative error (RE) ranged from -5.4% to 5.5%, and the intra-day and inter-day precisions expressed as relative standard deviation (RSD) were both below 7.6%, while the matrix effects ranged from 92.2% to 97.5%. The established method was applied to investigate the enantioselective degradation and accumulation of paclobutrazol enantiomers in soil and earthworms, respectively. The results indicated that the degradation process of paclobutrazol enantiomers in soil exhibited significant difference, with (2R,3R)-paclobutrazol being preferentially degraded. The biological action of earthworms significantly accelerated the degradation rate of paclobutrazol enantiomers in soil. Meanwhile, (2S,3S)-paclobutrazol exhibited a stronger tendency for bioaccumulation in earthworms. These findings provide a scientific basis for assessing the environmental risks of paclobutrazol enantiomers and for developing safer single-configuration paclobutrazol pesticides.