Abstract:

A new multi-residue methodology using liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) for the quantitative analysis of pesticides has been developed. The analytical performance of the method was evaluated by screening herbicide and insecticide residues in 10 kinds of imported soybeans. The accurate mass was obtained in different spiking levels (from 0.05 to 0.10 mg/kg) and the accuracy error was lower than 3×10-6, which is well within the accepted limits for target confirmation. The linearity of response ranged from 0.03 mg/kg to 1.0 mg/kg and the correlation coefficient was greater than 0.99. The average recoveries of herbicides and insecticides ranged from 60% to 120% of the fortified herbicides and insecticides in soybeans at 0.05-0.10 mg/kg levels for the majority of herbicides and insecticides, and the relative standard deviations (RSD) were between 2.17% and 13.54%. The limits of detection (LOD) were between 0.002 and 0.026 mg/kg. The results indicated that the method developed is easier, faster, and more sensitive. It also demonstrated that this method can meet the requirements for simultaneous determination of herbicides and insecticides in soybeans. This study provides valuable evidence for that LC-TOF-MS method has the potential in screening multi pesticide residues in soybeans.

Key words: insecticide residues, herbicide residues, screening, soybeans , high performance liquid chromatography-time-of-flight mass spectrometry (HPLC-TOF-MS)