Identification, Quantification, and Stereoselective Degradation of Triazole Fungicide Cyproconazole in Two Matrixes through Chiral Liquid Chromatography-Tandem Mass Spectrometry.

Abstract

Systematic investigation of cyproconazole, including absolute stereochemistry, fungicidal activity, quantification in two matrixes, and stereoselective degradation in cucumber, are conducted in this study. By virtue of vibrational circular dichroism (VCD) spectroscopy, absolute configurations of four stereoisomers were identified to be (2R,3R)-(+)-, (2R,3S)-(+)-, (2S,3S)-(-)-, and (2S,3R)-(-)-cyproconazoles. Then four stereoisomers exhibited stereoselective fungicidal activities against Fusarium graminearum Schw and Magnaporthe oryzae, and the order of fungicidal activity was (2S,3S)-(-)-stereoisomer > the stereoisomer mixture > (2S,3R)-(-)-stereoisomer > (2R,3R)-(+)-stereoisomer > (2R,3S)-(+)-stereoisomer. Moreover, chiral liquid chromatography-tandem mass spectrometry was used to identify and quantify cyproconazole stereoisomers in soil and cucumber matrixes. Good linearity (R2 ≥ 0.99) and recoveries (86.79-92.47%, RSD ≤ 3.94%) for them were achieved, individually. Furthermore, stereoselective degradation of four cyproconazole stereoisomers was observed in cucumber and the order of degradation rate was (2R,3R)-(+)-cyproconazole > (2S,3S)-(-)-cyproconazole > (2R,3S)-(+)-cyproconazole > (2S,3R)-(-)-cyproconazole. We envision that such systematic assessments of chiral fungicides at an enantiomeric level would provide valuable information in future studies involving enantioselective physiological, metabolic, and toxicological activities.