Summary. 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.

ABSTRACT. Considering the international situation regarding the residues of pesticides in vegetables and fruits and the requirement for sensitive and reliable analytical methods that are able to ensure the compliance of marketed food commodities with the law on food safety, the aim of this paper was the identification and determination of some degradation products and metabolites of ten most often used pesticides. Two analytical approaches are proposed and used for the development of reliable screening, quantification and confirmation of pesticides metabolites in different vegetables. The proposed methods have different approaches than the other multi-residue methods for vegetables allowing the extensive investigation of previously undetectable or unknown pesticide metabolites in vegetables. These methods were tested on cherry tomato, cucumber, and chili pepper, some of the most widely consumed vegetables. The results suggests that spraying pesticides in high doses lead to high levels of pesticide residues in the case of some studied vegetables and the concentration of metabolites together concentration of parent pesticide must be taken into account in order to establish the MRL's in vegetables and fruits.