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This study was undertaken to validate the "quick, easy, cheap, effective, rugged and safe" (QuEChERS) method using Golden Delicious and Starking Delicious apple matrices spiked at 0.1 maximum residue limit (MRL), 1.0 MRL and 10 MRL levels of the four pesticides (chlorpyrifos, dimethoate, indoxacarb and imidacloprid). For the extraction and cleanup, original QuEChERS method was followed, then the samples were subjected to liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) for chromatographic analyses. According to t test, matrix effect was not significant for chlorpyrifos in both sample matrices, but it was significant for dimethoate, indoxacarb and imidacloprid in both sample matrices. Thus, matrix-matched calibration (MC) was used to compensate matrix effect and quantifications were carried out by using MC. The overall recovery of the method was 90.15% with a relative standard deviation of 13.27% (n = 330). Estimated method detection limit of analytes blew the MRLs. Some other parameters of the method validation, such as recovery, precision, accuracy and linearity were found to be within the required ranges.

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The aim of this study was to investigate four insecticide residues in cucumbers with the aid of QuEChERS 2007.1 method. For method verification assessment, pesticide-free cucumber matrix was spiked with 0.1, 1 and 10 times of MRL for each pesticide. The QuEChERS-LC-MS/MS analytical method revealed that the detection limits of the insecticides were below the MRLs and the overall recovery of method was 97.7%. These figures were within the SANTE recovery limits (60-140%) and the values specified for the repeatability (≤20%). Cucumbers were collected from six different stands (A-F) at Çanakkale open markets for 6 weeks between 23 November and 28 December 2018. Residues of each sampling time and each stand were assessed. Acetamiprid residue of 257g and 236 µg/kg were detected in week 5 from stand B and in week 2 from stand E, respectively. These values are close to MRL (300 µg/kg). Formetanate hydrochloride residue of the week 3 from stand F (36.3 µg/kg) was more than MRL of 10 µg/kg. Pirimiphos methyl and chlorpyrifos residues were not detected in cucumbers. Theoretical maximum daily intake assessment showed that there was no chronic exposure risk for these four pesticides through cucumber consumption.