Development and validation of an analytical method for naled and dichlorvos in air

A new gas chromatographic method for analysis of the thio organophosphate pesticide naled and its transformation product dichlorvos (DDVP) was developed and validated. Naled and DDVP in air were trapped on XAD-4 resin. The pesticides were recovered from the resin with ethyl acetate. Ethyl acetate extract was analyzed for naled and DDVP by using a gas chromatograph equipped with a DB-5 Megabore capillary column and a nitrogen−phosphorus detector. The limits of quantitation for naled and DDVP were 0.05 and 0.10 μg/sample, respectively. Naled and DDVP trapped on the resin were stable over 21 days at −20 °C. Trapping efficiencies of naled and DDVP in the air samples were 74.5 ± 3.5% and 49.7 ± 3.3%, respectively. The newly developed method showed excellent results for the air samples collected at the application sites. Maximum observed concentrations of naled and DDVP at the application sites were 6.30 and 0.99 μg/m3, respectively. Keywords: Air sample; naled; dichlorvos; gas chromatography