Quantification of pesticide residues in gherkins by liquid and gas chromatography coupled to tandem mass spectrometry

Abstract

The monitoring of pesticide residues in fruits and vegetables is a great concern in public health and international trade. This study aims to assess the incidence and quantification of pesticides in gherkins cultivated in Turkey. The sample preparation was based on QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction. The residues were determined by in-house validated methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). This study included 109 pesticide residues, of which 85 were analysed by LC-MS/MS, and 24 were analysed by GC-MS/MS. Key method performance parameters investigated were linearity, limit of quantification (LOQ), accuracy, precision and measurement uncertainty. The LOQs ranged from 0.002 to 0.005 mg kg(-1). Of the 203 gherkin samples analysed, 57.6 % were free from the detectable level of residues. In 42.4 % of the samples, 15 different residues were found in measurable levels, of which 5 were non-approved in EU. Multiple pesticide residues were recorded in 17.2 % of the samples. In 7.9 % of the gherkin samples, the residue levels exceeded the maximum residue levels (MRLs). Among the residues, chlorothalonil (detected in 32 % of the samples), acetamiprid (16.3 %) and metalaxyl (and its enantiomer metalaxyl-M) (4.9 %) were the most frequently quantified pesticides.