Development of a low-consuming solvent extraction for determination of 36 multiclass pesticides in atmospheric particulate matter (PM2.5)

In the present study, a fast, miniaturized and low-consuming solvent extraction procedure has been developed for the simultaneous determination of 36 multiclass pesticides in PM2.5 samples. After optimization of GC-MS conditions, all compounds were separated within 20 min of runtime (Figure 1 ). The composition of extracting solvent also was optimized and 500 iJL of a binary mixture composed by 70 % of acetonitrile and 30% of ethyl acetate was chosen. A central composite design was applied for ultrasoundassisted- extraction optimization. The optimal conditions led to an extraction time of 17 minutes at 39 oc of temperature (Figure 2), extracting efficiently particle masses as low as 321 IJg of PM2.5. The matrix effect was also evaluated. The recoveries ranged from 72.1 % (endrin aldehyde) to 120% (sulfotep) with RSD ~ 20% for most pesticides. After validation, the method was applied in the determination of multiclass pesticides in 12 PM2.5 samples collected in the Baia de Todos os Santos region, Salvador, Bahia-Brazil. 25 pesticides were successfully identified and quantified, among them organophosphates prohibited by European Union and banned organochlorine. The average concentration considering the total volume of air sampled ranged from 0.88 pg m-3 to 255 pg m-3 for aldrin and endrin aldehyde, respectively. Malathion, chlorpyrifos, 4,4'-DDE, endrin aldehyde, A.-cyhalothrin and permethrin were detected with frequencies above 50%.