title: A multi-residue method for the determination of 90 pesticides in matrices with a high water content by LC-MS/MS without clean-up.
abstract: A method using QuEChERS extraction and LC-MS/MS in electrospray positive ionisation mode was developed and validated for the analysis of 90 pesticides in a high water content matrix (tomato) in a single chromatographic run. To assess the intra-laboratory reproducibility of the method, validation was conducted on four different days by two different analysts. The validation data was treated using a spreadsheet developed in-house, which sets the most appropriate model for linear fit by determining whether the residuals of the calibration curves are homocedastic or heterocedastic. A statistical test for the significance of regression was also carried out. Calibration was always matrix-matched and the curves were obtained over the range 0.0075-0.10 or 0.020-0.125 mg kg(-1). Identification of analytes was based on retention times and MRM ratios. Recoveries were assessed at four different levels for each analyte and were between 73 and 106%, with relative standard deviations under reproducibility conditions of <20%. The measurement uncertainties of the method for each pesticide analysed were below 50%. Previous validation of the same method, applied to papaya samples and satisfactory results obtained in various proficiency tests with different high water content matrices, demonstrated the applicability of the method to these classes of commodities, without clean-up. The validated method will be applied routinely in the pesticide residues monitoring programme that constitutes the National Residue and Contaminant Control Plan of Brazil.
authors: Ministry of Agriculture, Livestock and Food Supply of Brazil, Laboratório Nacional Agropecuário (LANAGRO/MG), Pesticide Laboratory, Av. Rômulo Joviano, s/n Pedro Leopoldo, MG 33600-000, Brazil. fernando.madureira@agricultura.gov.br
authors: Fernando Diniz
authors: FD
authors: Madureira
authors: Fabiano Aurélio
authors: FA
authors: da Silva Oliveira
authors: Wesley Robert
authors: WR
authors: de Souza
authors: Ana Paula
authors: AP
authors: Pontelo
authors: Mauro Lúcio Gonçalves
authors: ML
authors: de Oliveira
authors: Gilsara
authors: G
authors: Silva
mesh_terms: D001938:Brazil; D002853:Chromatography, Liquid / Q000379:methods*; D005504:Food Analysis / Q000379:methods / Q000592:standards; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control / Q000706:statistics & numerical data; D005638:Fruit / Q000737:chemistry; D057230:Limit of Detection; D018551:Solanum lycopersicum / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis* / Q000592:standards; D012015:Reference Standards; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014675:Vegetables / Q000737:chemistry; D014867:Water / Q000032:analysis
chemical_list: D010573:Pesticide Residues; D014867:Water