Simultaneous Determination of the Residues of Isopyrazam Isomers and Their Metabolites in Soil and Tomatoes by Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry

Abstract

An effective and sensitive method for the determination of isopyrazam (IZM) isomers (syn-IZM and anti-IZM) and their metabolites (syn545364 and syn545449) in tomato and soil by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed in the present study. The method showed excellent linearities (R 2 = 0.999) at 0.005–5 mg/L. The recoveries were 92.0–107%, and the relative standard deviation (RSD) values were lower than 9.40% in tomato and soil matrices at 0.01, 0.1, and 10 mg/kg. The limits of detection (LODs) of the four compounds ranged from 6.88 × 10–5 to 2.70 × 10–4 mg/kg, while the limits of quantification (LOQs) ranged from 2.20 × 10–4 to 9.20 × 10–4 mg/kg. The storage stability test results showed that syn-IZM, anti-IZM, syn545449, and syn545364 were stable in tomato at −20 °C within 36 weeks, and the maximum degradation rates were 16.0, 12.0, 7.10, and 12.0%, respectively. The field dissipation test results showed that the half-lives of syn-IZM in tomato and soil were 2.60–10.2 and 13.6–33.0 days, respectively, while the half-lives of anti-IZM in soil were 21.7–46.2 days, and no residues of anti-IZM were detected in tomato. The terminal residue test results showed that the residue of syn-IZM and anti-IZM in tomato ranged from <0.0100–0.490 to <0.0100–0.0850 mg/kg. The present results showed that anti-IZM degraded faster than syn-IZM in tomato and soil, and had a lower residue level in tomato.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion

“…In this study, double recommended dose (Table S2) of four pesticides were selected to investigate the dynamic behavior of pesticide parents and their relevant metabolites. 1.5–5 times of the recommended dose was often used for investigating the dissipative dynamics of pesticides 28, 29 . One kilogram of fresh tea leaves were randomly collected from the experimental plots at 0, 3, 5, 7, 10, 14, 21, 28 and 35 days after the application.…”

“…1.5-5 times of the recommended dose was often used for investigating the dissipative dynamics of pesticides. 28,29 One kilogram of fresh tea leaves were randomly collected from the experimental plots at 0, 3, 5, 7, 10, 14, 21, 28 and 35 days after the application.…”