Validation and application of an analytical method for determining pesticides in the gas phase of ambient air

A method for determining atmospheric concentrations of eight pesticides applied to corn and soybean crops in Mato Grosso state, Brazil is presented. The method involved a XAD-2 resin cartridge coupled to a low volume air pump at 2 L min⁻¹ over 8 hours. Pesticides were recovered from the resin using sonication with n-hexane:ethyl acetate and determined by GC-MS. Good accuracy (76-128%) and precision (CV < 20%) were obtained for atrazine, chlorpyrifos, alpha- and beta-endosulfan, endosulfan sulfate, flutriafol, malathion, metolachlor and permethrin. Method detection ranged from 9.0 to 17.9 ng m⁻³. This method was applied to 61 gas phase samples collected between December 2008 and June 2009. Atrazine and endosulfan were detected both in urban and rural areas indicating the importance of atmospheric dispersion of pesticides in tropical areas. The simple and efficient extraction method and sampling system employed was considered suitable for identifying pesticides in areas of intense agricultural production.