Multiresidue Analysis of Pesticides and Metabolites from Fruits and Vegetables by Gas Chromatography—Time-of-Flight Mass Spectrometry

Abstract

This work describes the comparison of five sample extraction methods for the determination of pesticide residues in grapes and vegetables by using gas chromatography—time-of-flight mass spectrometry (GC—TOF-MS). These methods were based on original methods QuEChERS, mini-Luke, ethyl acetate, and DIN EN 15637, and some of these were slightly modified to increase the number of identified and quantified pesticides, to improve their quantification limits, and to be fast and less expensive in terms of material cost. The acceptable performance parameters combined with the properties of easy and quick handling and cost-effectiveness have made mini-Luke modified extraction method as the most favorable in the pesticide residues analysis from grapes and tomatoes by GC—TOF-MS. The efficiency of the chosen extraction method was also verified for lettuce; for this matrix, a cleanup step with graphitized black carbon (GBC) was added. Analysis of extracts was carried out by GC—TOF-MS within 29.2 min run time. The GC method was validated for grapes and tomatoes in terms of linearity, accuracy, limit of detection (LOD), and limit of quantification (LOQ). Good linearity with correlation coefficients ( r ²) higher than 0.98 was obtained. For most analytes from both matrices, recoveries were in the range of 71–120% and LOQ values in the range of 0.01–0.05 mg kg ⁻¹. The GC—TOF-MS and modified mini-Luke extraction methods were successfully tested on real vegetable and fruit samples belonging to the same commodities group as those from validated methods according to European Guide DG SANCO 12571/2013 (tomatoes, pepper, cucumber, potatoes, carrots, eggplants, onion, lettuce and grapes) and in proficiency EU tests.