Dissipation kinetics and residues of amidosulfuron and MCPA in wheat ecosystems based on a modified QuEChERS and low-temperature cleanup method using the RRLC-QqQ-MS/MS technique

Abstract

A simple, quick and efficient approach for simultaneous determination of amidosulfuron and MCPA in wheat field ecosystems was established and validated through rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS) combined with a modified QuEChERS method with low-temperature cleanup technology. The matrix-matched external calibrations were carried out to eliminate matrix effects. The limits of quantification (LOQs) in soil, wheat grain and wheat straw were 0.002, 0.002 and 0.005 mg kg⁻¹ for amidosulfuron, and 0.02, 0.02 and 0.05 mg kg⁻¹ for MCPA, respectively. The mean recoveries (n = 5) for both amidosulfuron and MCPA in wheat ecosystems varied from 83.14% to 103.83%, from 93.29% to 114.26% with the relative standard deviations (RSDs < 16.45%) at three fortifications. The dissipation kinetics remarkably followed the pseudo-first-order kinetic models. The half-lives of amidosulfuron ranged from 1.30 to 7.99 days in wheat straw and from 2.33 to 18.58 days in soil, whereas those of MCPA ranged from 0.48 to 6.74 days in wheat straw and from 3.10 to 22.22 days in soil at the three representative locations. The terminal residues were much lower than the maximum residue limits (MRLs) of amidosulfuron in triticeae crop recommended by China (0.01 mg kg⁻¹), and the MRLs of MCPA in triticeae registered by the European Union (0.05 mg kg⁻¹), America and Japan (0.1 mg kg⁻¹). These findings were of utmost importance for providing scientific and basic information about the dissipation kinetics and the safety evaluation of amidosulfuron and MCPA in wheat ecosystems.