Novos procedimentos de extração aplicados à análise de agrotóxicos usando amostragem passiva, cromatografia gasosa convencional e bidimensional abrangente

Abstract

The production, trade, and consumption of pesticides in Brazil have increased considerably in the last two decades. Although pesticide applications increase the production of different agricultural products, these compounds are toxic to the environment and human health. They cause different types of diseases, such as cancer and fetal malformation, besides, mortality of aquatic organisms. The development of new techniques to assess pesticides in water sources is a challenge for analytical chemistry. This work presents the development of three new systems for the extraction of pesticides based on techniques of solid phase microextraction with carbon nanomaterials (SPME-CNMs) and hollow fiber - liquid phase microextraction (HF-LPME). The first one is an SPME-CNMS syringe to analyze samples collected by grab sampling and the second and third are passive sampling devices with SPME-CNMs and HF-LPME systems respectively. Each extraction system involves an analytical method, which has been optimized and validated in the laboratory, showing good results in the different figures of merit evaluated. The analytical methods showed linearity in the different concentration ranges evaluated with determination coefficients greater than 0.9506. On the other hand, the limits of detection and quantification were between the ranges of 1×10-4 μg L-1 to 1.13 μg L-1, and between 3×10-4 μg L-1 to 3.73 μg L-1 respectively. The studied pesticides presented recovery values in the range of 70% to 140%. The different pesticides were separated, detected, and quantified using gas chromatography and comprehensive two-dimensional gas chromatography coupled to mass spectrometry The samplers were calibrated in the laboratory where the exposure times and passive sampling rates determined are in the ranges of 3 to 18 days and from 0.014 to 23.15 mL d-1 respectively. The Samplers and the syringe were applied to analyze environmental water from the San Francisco River basin in the state of Minas Gerais in Brazil. Among the pesticides found are organophosphate compounds such as diazinon, pirimiphos Methyl, and fenitrothion and organochlorine compounds such as 4,4-DDD, 4,4-DDE, and α HCH. On the other hand, trifluralin and diazinon were the most detected pesticides.