Método multirresíduo para agrotóxicos e compostos relacionados em ar empregando trapeamento em sorvente polimérico e GC-MS/MS

Abstract

While pesticides are applied to crops in order to control pests and thereby increase productivity, these substances can undergo processes such as volatilization, dispersion and transport, reaching the atmosphere, soil and water. Thus, this study aimed to develop and validate a method for the determination of 48 pesticides and related compounds in air, based on active sampling using a trapping device home-made, with subsequent solvent extraction of analytes and determination by Gas Chromatography coupled to Tandem Mass Spectrometry (GC-MS/MS), as well as demonstrate the applicability of the proposed method in local storage and marketing of these compounds, checking the exposure of workers. The sampling system consists of a vacuum pump to force the passage of air through the traps and a flow meter for controlling the volume of air sampled. Whereas various compounds studied have medium volatility, it was used a heater for heating the first trap, where the spike process is carried out with the compounds under study. A set of three traps glass with dimensions of 12.5 cm long x 3 mm inner diameter x 5 mm external diameter, connected by silicone connectors, complete the device used. It was used the 24 factorial design for optimization of sampling and elution, where conditions were defined as: flow of 87.5 mL min-1 sampling time of 8 h, volume of acetone for elution of 5 mL and greenhouse temperature of 60 ºC. The extract was filtered and analyzed by GC-MS/MS. The accuracy and precision of the method was verified with recovery tests of at least three concentration levels for each analyte, yielding values between 70.0 and 120.0% for most of the compounds evaluated. Most RSD values lower than 20% ensured the precision of the method. Method LOQ values were 3.0 or 6.0 μg m-3, depending on the analyte, considered appropriate to control the exposure of these compounds in air. The method was applied in company that stores and sells pesticides and in the standards preparation room in laboratory of analysis of pesticides residue, in which no residues were found for the studied compounds. The sampling and elution method proposed was effective for most compounds and can be applied in the determination of pesticides and related compounds in air samples.