Simultaneous determination of metolachlor, pendimethalin and oxyfluorfen in bulb vegetables using gas chromatography-tandem mass spectrometry

Abstract

A sensitive and effective method using the QuEChERS procedure for simultaneous determination of metolachlor, pendimethalin and oxyfluorfen residues in bulb vegetables (garlic, Chinese onion, onion, garlic stem and leek) was developed using GC-MS/MS. Samples were extracted with acetonitrile and cleaned-up with primary secondary amines (PSA). The method showed excellent linearity (R² > 0.997) for target compounds. The limits of quantitation (LOQ) objective for which the method was satisfactorily validated in five samples matrices was 5 μg kg⁻¹ and the limit of detection (LOD) ranged from 0.5 μg kg⁻¹ to 2.3 μg kg⁻¹. Average recoveries in five bulb vegetables at four levels (0.005, 0.025, 0.1 and 1 mg kg⁻¹) ranged from 77.5% to 114.2% with relative standard deviations (RSD_r) from 1.8% to 14.9%. The reproducibility RSD_R ranged from 3.9% to 15.0%. This method was successfully applied for the analysis of real samples, confirming the applicability of the method.