Desenvolvimento, validação e aplicação de um protocolo analítico para determinação do pesticida alaclor em água superficial

Abstract

The use of agrochemicals, for the purpose of combating pests and allowing large scale plantations, is increasingly common. Therefor, studies related to the presence of pesticides in the environment are necessary to evaluate their influence on matrices such as water, sediment, soil and air. According to it, the focus of the study was the development, validation and application of an analytical protocol for the determination of an herbicide, alachlor, in surface water of water bodies. The samples were collected in thre campaigns, in the city of Arapongas / PR. The sample preparation procedure consisted of solid phase extraction (SPE) with Bond Elut C18 200 mg cartridge and the chromatographic separation performed by high performance liquid chromatography (HPLC) with Poroshel 120 - C18 column and detection by arrangement of diodes in the ultraviolet / visible range, at the wavelength of 203 nm. The analytical development, from extraction to determination, was evaluated in triplicate at three concentrations obtaining recoveries from 82.30 to 116.72% in the environmental matrix. The validation was carried out in ultrapure water and surface water, and the exact method was considered. In the analysis of surface water validation, the analytical curve was made in triplicate, obtaining a detection limit of 0.68 µg L-1 and a quantification limit of 2.05 µg L-1. In the first sampling campaign the presence of alachlor was observed only in P4. In the second collection, alachlor was detected at three distinct points in the concentration range of 3.33 to 8.40 µg L-1. In both sample campaigns, P4 presented concentrations ranging from 9.65 to 7.48 µg L-1. This region is under evaluation by the Public Ministry of the State of Paraná due to suspected contamination by pesticides. Thus, in this study the presence of alachlor has been proven, although it has been banned for commercialization since 2013 in Brazil. However, the concentration of alachlor is below that established by CONAMA legislation for surface fresh waters class I and II.