Enantioselective separation and determination of mefenpyr‑diethyl enantiomers in cereals and soil using high-performance liquid chromatography-tandem mass spectrometry

A simple and highly-sensitive method was established and validated for analyzing mefenpyr‑diethyl enantiomers in cereals and soil samples with HPLC-MS/MS. The baseline enantioseparation (resolution value=6.73) of mefenpyr‑diethyl was achieved within 10.5 min using cellulose-tris [4-methylbenzoate] (OJ-RH column) as chiral station phase. The influence of different mobile phase composition, flow rates and the column temperature on the chiral resolution of mefenpyr‑diethyl were investigated. The five selected sample matrices (four type of cereal crops and soil) were firstly extracted with acetonitrile and then purified with the dSPE sorbents. Satisfactory linearity was afforded for both two enantiomers of the target chiral compound over a range of concentrations (1–500 µg/L) in solvent and in the five matrices (r>0.9994). The mean recoveries of two enantiomers of mefenpyr‑diethyl from five matrices were ranged from 85% to 104%, with all relative standard deviations (RSDs) values below 10.6%. The limits of quantification (LOQ) were 5 µg/kg for mefenpyr‑diethyl enantiomers in all studied matrices, and the limits of detection (LOD) ranged from 0.03 to 0.13 µg/L. Hence, the new method provides a reference for further research on enantioselective environmental behaviors of mefenpyr‑diethyl in cereal plants and soil.