Pesticide Residues Method Validation by UPLC-MS/MS for Accreditation Purposes

• Published in: Journal of the Brazilian Chemical Society Vol. 27; no. 7; pp. 1165 - 1176
• Main Authors: Pizzutti, Ionara R., Dias, Jonatan V., Kok, André de, Cardoso, Carmem D., Vela, Giovana M. E.
• Format: Journal Article
• Language: English; Portuguese
• Published: Sociedade Brasileira de Química 01.06.2016
• Subjects: CHEMISTRY, MULTIDISCIPLINARY; Dutch mini-Luke method; UPLC-MS/MS; accreditation; pesticides; validation
• ISSN: 1678-4790
• DOI: 10.5935/0103-5053.20160012

The development and validation of an analytical method for the determination of 51 pesticides in tomato using UPLC-MS/MS (ultra performance liquid chromatography coupled to tandem mass spectrometry) was performed in order to fulfill the requirements of the NBR ISO/IEC 17025:2005. The goal of the validation was to evaluate all required parameters, such as linearity of analytical curves, instrument and method limits of detection and quantification, matrix effect and accuracy (trueness and precision). Stock solutions of the pesticides were prepared in organic solvent by two different analysts independently, in order to validate this preparation by comparing the detector response areas of injections (n = 7). Pesticides were extracted from tomatoes applying the Dutch mini-Luke method with 30 mL of each solvent as acetone, petroleum ether as well as dichloromethane. A small aliquot of the organic solvent extract was evaporated and reconstituted in methanol with 0.1% of acetic acid (v/v) for UPLC-MS/MS analysis. The recovery experiments were done by spiking blank samples at 10, 20 and 50 µg kg-1, performed by two analysts, seven replicates for each concentration level plus the blank sample. From the 51 studied compounds, 46 showed recoveries within the acceptable range of 70-120% for all evaluated concentrations. For 82% of pesticides, the validated method limit of quantification was the lowest concentration studied (10 µg kg-1) . The intermediate precision was below 20% for all evaluated pesticides showing excellent repeatability of the method.