Desenvolvimento de método cromatográfico para determinação de pesticidas em fase gasosa utilizando amostradores de baixo volume

Abstract

A method for determination of trifluralin, atrazine, alachlor and chlorpyrifos in gas phase using polyurethane foam (PUF) and styrene-divinylbenzene polimeric resin (XAD-2) was developed. The sampling was performed by using low volume samplers at 4.0 L min-1 over 24 h. The pesticides were extracted using ultrassonic bath with acetone and determined by GC-MS/MS. The chromatographic peaks presented good resolution and selectivity. The method was applied in samples of gas phase collected in the city of Arapongas/PR between the months of February and November of 2017. Samples were collected at UTFPR/Curitiba in order to minimize the matrix effects. One, two and three cycles of extraction were evaluated and the extraction with two cycles was chosen. Good recoveries for this extraction were obtained for trifluralin, atrazine, alachlor and chlorpyrifos both in PUF (75.1 – 117.8%) and in XAD-2 (71.2 – 109.4%) in two levels of concentration. Limits of detection using matrix-standard calibrations solutions ranged from 24.1 to 63.1 pg m-3 in PUF and from 70.0 to 101.5 pg m-3 in XAD-2. Maximum concentrations of 1189 pg m-3 were found for the trifluralin and 1345 pg m-3 for the atrazine. Chlorpyrifos was the analyte that presented greater concentration, with a value of 3062 pg m-3 between the months of September and November. Alachlor was detected in a few months but was not quantified due the values below the limit of quantification. The concentrations of chlorpyrifos resemble those found in other studies in agricultural regions. The increase in the concentrations of trifluralin and atrazine may be related to the presence of an industrial area near the collection points of the samples where these compounds are manipulated.