Determinação de multirresíduos de agrotóxicos em água empregando SPE automatizado e GC-MS/MS: desenvolvimento, validação e monitoramento ambiental

Abstract

This work presents the optimization and validation of a multi-residue method, using automated solid-phase extraction and gas chromatography tandem mass spectrometry, for the determination of 63 pesticides in treated water and 56 in raw water. The optimized extraction condition used an Oasis HLB 6cc cartridge (200 mg), 200 mL of sample (pH 4), cartridge cleaning with 3 mL of ultrapure water (pH 4), analyte extraction with 2,5 mL of acetonitrile:ethyl acetate (1:1 v/v) fractionally, evaporation of the extract at 40°C, and resuspension in 200 μL of acetonitrile:ethyl acetate (1:1 v/v) with addition of 5% v/v of the analyte protectant (gluconolactone and d-sorbitol). Method validation was based on the criterial and recommendations of SANTE/2020/12830 from the European Union. The quantification limits ranged from 0.010 to 0.080 μg L-1, recovery percentages were between 81 and 120% for 96.8% of the evaluated pesticides, and the relative standard deviation was less than 20%. The validated method was submitted to two proficiency tests by Sabesp, which proved to be proficient in the analysis of the evaluated pesticides. The method was implemented at the Laboratório de Resíduos de Agrotóxicos of the Funed, a reference laboratory for pesticide analysis in Brazil. The analysis of 57 samples of water for human consumption, collected in different cities in Minas Gerais by the environmental surveillance, showed that 30% had contamination below the maximum permitted value established by the Ministério da Saúde.