LC-MS/MS method for simultaneous determination of myclobutanil, hexaconazole, diniconazole, epoxiconazole and tetraconazole enantiomers in soil and earthworms

A new method using gel permeation chromatography (GPC) clean-up followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of myclobutanil, hexaconazole, diniconazole, epoxiconazole and tetraconazole enantiomers in soil and earthworms. The soil and earthworm samples were extracted with acetonitrile and then purified with a GPC procedure conducted on a CO785 column with cyclohexane and ethyl acetate (50:50, V/V) as the mobile phase at a flow rate of 4.7 mL/min. The eluent between 7.5 min and 15 min was collected for LC-MS/MS analysis. The LC mobile phase and MS/MS conditions were optimised. Formic acid (0.1%, V/V) was added to the water phase to enhance MS responses. The LODs of the enantiomers were between 0.001–0.003 mg/kg. At three fortification levels of 0.01–1.00 mg/kg, recoveries were between 81.2% and 100.2% in soil and earthworms. The relative standard deviation was below 14%. The results of earthworm experiment showed that hexaconzole and diniconazole might have the bioaccumulation potential, whereas tetraconazole, epoxiconazole and myclobutanil were most likely to undergo enantioselective biotransformation. On the contrary, the degradation of the triazoles in soil was achiral, and less than 10% of them were degraded after 21 days.