Enantioselective determination of phenthoate enantiomers in plant-origin matrices using reversed-phase high performance liquid chromatography-tandem mass spectrometry.

Abstract

Phenthoate is a chiral organophosphate pesticide with a pair of enantiomers which differ in toxicity, behavior, and insecticidal activity, and its acute toxicity on human health due to the inhibition of acetylcholinesterase highlights the need for enantioselective detection of enantiomers. Therefore, this study is aimed to establish a simple rapid method for separation and detection of phenthoate enantiomers in fruits, vegetables, and grains. The enantiomers were separated using reversed-phase high performance liquid chromatography-tandem mass spectrometry (RP-HPLC-MS/MS) for the first time. Rapid chiral separation (within 9 min) of the target compound was achieved on a chiral OJ-RH column with the mobile phase of methanol/water=85/15(v/v), at a flow rate of 1 mL/min and column temperature of 30 °C. Acetonitrile and graphitized carbon black were used as the extractant and sorbent for pretreatment, respectively. This method provides excellent linearity (correlation coefficient no less than 0.9986), high sensitivity (limits of quantification at 5 μg/kg and limits of detection less than 0.25 μg/kg), satisfactory mean recoveries (76.2% to 91.0%) and relative standard deviations (intra-day RSDs ranged from 2.0% to 7.9% and inter-day RSDs ranged from 2.4% to 8.4%). In addition, field trial to explore the stereoselective degradation of phenthoate enantiomers in citrus showed that (-)-phenthoate degraded faster than its antipode, resulting in the relative accumulation of (+)-phenthoate.