Abstract
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.
Highlights
Since 2008, Brazil has had the worrying position of being the largest consumer of pesticides in the world
For the accreditation of testing laboratories, it is necessary to validate methods developed in the laboratory itself to prove its ability to perform certain analyses through validation parameters required by the official accreditation standard for testing laboratories, the International Organization for Standardization (ISO)/IEC 17025 norm
A method for determination of 51 pesticides was developed and validated according to the parameters required by the Brazilian accreditation body (INMETRO/CGCRE) and in accordance with ISO/IEC 17025 as a prerequisite for laboratory application to be accredited
Summary
Since 2008, Brazil has had the worrying position of being the largest consumer of pesticides in the world. The extensive use of pesticides is a serious public health problem in developing countries, especially those with economies based on agribusiness, as is the case in Brazil. The Program on Pesticide Residues Analysis in Food (PARA), coordinated by the National Health Surveillance Agency (ANVISA), aims to analyze fruits and vegetables sold. There is a need to develop rapid and accurate analytical methods for determination of pesticide residues in agricultural products, including a wide range of pesticide groups, with very different properties (polar, non-polar, planar, acids, bases), and doing that in a single chromatographic run and one extraction per sample.[3,4]. Considering the increase in the use of pesticides in various cultures, there is a growing need for government agencies to carry out control programs to determine the occurrence of residues and their concentrations. The main difficulty in developing reliable methods is the lack of enough laboratories in Brazil with competence on identification and quantification of these substances
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