Fast supercritical fluid extraction and high-resolution gas chromatography with electron-capture and flame photometric detection for multiresidue screening of organochlorine and organophosphorus pesticides in Brazil’s medicinal plants

A description is given of a rapid and environmentally friendly method to determine organochlorine and organophosphorus pesticide multiresidues—malathion, methidathion, fenitrothion, fenthion, parathion-ethyl, parathion-methyl, lindane, hexachlorobenzene, chlorothalonil, tetradifon, α-endosulfan, β-endosulfan and dieldrin—in Passiflora alata Dryander and Passiflora edulis Sims. f. flavicarpa Deg. leaves by supercritical fluid extraction and high-resolution gas chromatography with electron-capture and flame photometric detection (HRGC–ECD/FPD). The mild extraction conditions [pure CO2; 100 bar (1 bar=105 Pa) and 40 °C (ρ=0.62 g/ml); 5 min static+10 min dynamic extraction time; ODS trap and elution with 1 ml n-hexane at 2 ml/min] allow for direct analysis by HRGC–ECD/FPD with no prior cleaning procedure. The method provides, in accordance with the validation criteria of the European Pharmacopoeia, analytical results that are similar or even better than the official procedures, and is simpler, faster and cheaper. Mean recoveries of 69.8–107.1% were obtained, with 1.4–14.7% reproducibility (RSD). The method was applied to analyse commercial samples of Passiflora L. from Brazil. Twenty-three percent of the samples showed the presence of the organochlorine or organophosphorus pesticide residue investigated.