Abstract

Pesticide registration ensures the safety of agricultural products; however, the backlog of field samples often requires lengthy storage periods. Thus, the stability of pesticide residues in stored samples is required information for pesticide registration. We monitored the degradation rates of fluroxypyr and halosulfuron-methyl in maize straw, mature maize grain, and fresh corn matrices to evaluate their storage stability. Analytes were extracted and cleaned up with a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method and then detected with liquid chromatography tandem-mass spectrometry. We optimized the workflow by testing different clean-up sorbents, LC columns, and chromatographic methods. The linearity correlation coefficients of fluroxypyr and halosulfuron-methyl in the three matrices were ≥0.994. At three fortification levels, the mean recoveries of fluroxypyr and halosulfuron-methyl were 84.2–114.8% and 83.8–105.5% with relative standard deviations of 2.4–9.4% and 2.7–10.2%, respectively. Degradation of the two herbicides in the three matrices was less than 30% over the 70-day storage period, indicating fluroxypyr and halosulfuron-methyl are stable in the tested maize matrices when stored at −20 °C for at least 70 days. This study provides a reference method for pesticide residue analysis and can be used as a guide to develop accurate and reasonable pesticide registration procedures.

摘要

农药注册确保了农产品的安全；但是，现场样品的积压通常需要较长的存储时间。因此，存储样品中农药残留的稳定性是农药注册所需的信息。我们监测了玉米秸秆，成熟玉米籽粒和新鲜玉米基质中氟草烟和卤代磺隆的降解速率，以评估其储存稳定性。使用改进的快速，简便，廉价，有效，坚固耐用和安全的方法（QuEChERS）提取并净化分析物，然后用液相色谱串联质谱法进行检测。我们通过测试不同的净化吸附剂，LC色谱柱和色谱方法来优化工作流程。三种基质中氟草烟和甲基氟磺隆的线性相关系数≥0.994。在三个设防水平下，氟草烟和甲基氟磺隆的平均回收率分别为84.2–114.8％和83.8–105.5％，相对标准偏差分别为2.4–9.4％和2.7–10.2％。在70天的存储期内，这三种基质中的两种除草剂的降解率均低于30％，这表明当在-20°C下存储至少70天时，氟草烟和卤代磺隆在测试的玉米基质中是稳定的。该研究为农药残留分析提供了参考方法，可作为制定准确合理的农药注册程序的指南。在70天的存储期内，这三种基质中的两种除草剂的降解率均低于30％，这表明当在-20°C下存储至少70天时，氟草烟和卤代磺隆在测试的玉米基质中是稳定的。该研究为农药残留分析提供了参考方法，可作为制定准确合理的农药注册程序的指南。在70天的存储期内，这三种基质中的两种除草剂的降解率均低于30％，这表明当在-20°C下存储至少70天时，氟草烟和卤代磺隆在测试的玉米基质中是稳定的。该研究为农药残留分析提供了参考方法，可作为制定准确合理的农药注册程序的指南。