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Multiresidue analysis of pesticides in tomatoes using LC-MS/MS and evaluation of the effects of washing in decontaminating

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Author(s):
Graziela Cristina Rossi de Moura Andrade
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba.
Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
Defense date:
Examining board members:
Valdemar Luiz Tornisielo; Fabio Augusto; Regina Prado Zanes Furlani; Amir Bertoni Gebara; Isabel Cristina Sales Fontes Jardim
Advisor: Valdemar Luiz Tornisielo
Abstract

Pesticides have been widely used in agriculture to control pests, diseases and weeds. The intensive use of pesticides in tomato crops disrespecting good agricultural practices have been causing concerns about the possible contamination of the final product and many multiresidue methods have been used in order to evaluate and determine the levels of residues in food samples. Therefore, the aim of this study was validate the method using QuEChERS sample preparation and LC-MS/MS for quantification of 61 pesticides residues from different chemical classes in tomato. Detection was performed using mass spectrometry in dynamic MRM mode, run time had 13 min and analytical column packed with 1,8 \'mü\'m particles. Of the 61 pesticides studied, 46 are in accordance with the validation parameters of the European Commission and ANVISA, 15% of the validated pesticides presented matrix effect, recoveries were between 87 and 116% and coefficient of variation 5 to 17%. More than 85% of the compounds investigated showed limits of detection less or equal than 5 \'mü\'g kg-1 and the limits of quantification less or equal than 10 \'mü\'g kg-1. 58 real samples of tomato were analyzed and collected in supermarkets in Piracicaba, SP, Brazil. Twelve compounds were detected in thirty-five samples (60% of the total analyzed), all below the maximum residue limit allowed in Brazil for acephate, acetamiprid, azoxystrobin, benalaxyl, bromuconazole, diflubenzuron, imidacloprid, iprodione, prochloraz and thiamethoxam, and 15 positive samples of methamidophos and 1 for oxamyl, which are not authorized to use at the culture of tomatoes. A wash study was conducted with spiked tomatoes using formulated products (8 pesticides) with water, 10% acetic acid, 10% sodium bicarbonate solution and analyzed concentration in the peel and pulp, in order to evaluate the capacity to remove pesticides in each procedure. All wash treatments (n= 3) differed significantly for all pesticides evaluated (n= 8), with the exception of fipronil, which the washing with 10% of sodium bicarbonate solution and water no showed difference in the level of significance 5%. The washing with water or other solutions before consumption is indicated for the reduction of pesticide residues in tomatoes and the peeling also contributes to this reduction (AU)

FAPESP's process: 09/15816-0 - Multiresidue analysis of pesticides in tomato using LC-MS/MS and evaluation the effects of washing in decontamination.
Grantee:Graziela Cristina Rossi Moura Andrade
Support Opportunities: Scholarships in Brazil - Doctorate