Multirresidue determination of pesticides in sweet Pepper by modified QuEChERS method and UHPLC-MS/MS

In recent years, the indiscriminate use of pesticides and non-adoption of good agricultural practices have been evidenced by the results of analysis of pesticide residues in food, such as sweet pepper, one of Brazilian record holders with active ingredients that are banned or above the recommended limits. Thus, the present study aimed to develop and validate a rapid method for the determination of 83 pesticides in sweet pepper using modified QuEChERS method and Ultra-high Performance Liquid Chromatography coupled to tandem Mass Spectrometry (UHPLC-MS/MS). In the sample preparation extraction/partition procedures, and different sorbents for clean-up were tested, such as diatomaceous earth and polymeric sorbent. It was used the 24 factorial design for optimization of the method of extraction, which consisted of the extraction of 10.0 g sweet pepper with 10.0 mL of acetonitrile. In the partition step 1.5 g of NaCl, 4.0 g MgSO4 were added, carrying out shaking and centrifugation. It was carried out the clean-up step of 1.0 ml of extract with 40.0 mg of PSA and 150.0 mg of MgSO4, followed by shaking and centrifugation. The extract was filtered, diluted and analyzed by UHPLC-MS/MS. Most compounds showed linear range (r2 ≥ 0.99).The matrix effect was compensed by using analytical curves prepared in blank matrix-matched. The accuracy of the method was verified by testing recovery at four concentration levels, yielding values between 70.0 and 120.0% for most compounds evaluated. Values of LODm and LOQm were 3 or 7.5 μg kg-1 and 10 or 25 μg kg-1, respectively. RSD values lower than 20% ensured good precision of the method. The method was performed on 20 samples of sweet pepper, in which residues of acetamiprid, azoxystrobin, boscalid, carbendazim, chlorpyrifos ethyl, clothianidin, difenoconazole, fenpropathrin, pyraclostrobin and pyrimethanil were quantified in concentrations ranging from 10 to 294 μg kg-1. The proposed modified QuEChERS method for the determination of 81 from 83 pesticide residues in sweet pepper using UHPLC-MS/MS shown to be effective and can be applied in routine analysis.