Simultaneous enantioselective determination of triadimefon and its metabolite triadimenol in edible vegetable oil by gel permeation chromatography and ultraperformance convergence chromatography/tandem mass spectrometry.

Abstract

A novel, sensitive, and efficient enantioselective method for the determination of triadimefon and its metabolite triadimenol in edible vegetable oil, was developed by gel permeation chromatography and ultraperformance convergence chromatography/tandem triple quadrupole mass spectrometry. After the vegetable oil samples were prepared using gel permeation chromatography, the eluent was collected, evaporated, and dried with nitrogen gas. The residue was redissolved by adding methanol up to a final volume of 1mL. The analytes of six enantiomers were analyzed on Chiralpak IA-3 column (150 × 4.6mm) using compressed liquid CO2-mixed 14% co-solvents, comprising methanol/acetonitrile/isopropanol = 20/20/60 (v/v/v) in the mobile phase at 30°C, and the total separation time was less than 4min at a flow rate of 2mL/min. Quantification was achieved using matrix-matched standard calibration curves. The overall mean recoveries for six enantiomers from vegetable oil were 90.1-97.3%, with relative standard deviations of 0.8-5.4% intra-day and 2.3-5.0% inter-day at 0.5, 5, and 50μg/kg levels. The limits of quantification were 0.5μg/kg for all enantiomers based on five replicate extractions at the lowest fortified level in vegetable oil. Moreover, the absolute configuration of six enantiomers had been determined based on comparisons of the vibrational circular dichroism experimental spectra with the theoretical curve obtained by density functional theory calculations. Application of the proposed method to the 40 authentic vegetable oil samples from local markets suggests its potential use in enantioselective determination of triadimefon and triadimenol enantiomers. Graphical Abstract Chemical structures and UPC(2)-MS/MS separation chromatograms of triadimefon and triadimenol.