Funnelform single-drop microextraction for gas chromatography–electron-capture detection

A funnelform single-drop microextraction was developed for gas chromatography–electron-capture detection. A solvent microdrop of 4 μL was formed at the tip of a microsyringe needle assembled with a small brass funnel in the microextraction. In the funnel, the restricted microdrop was shaken gently by circular motion in an aqueous sample solution. Eleven organochlorine and two pyrethroid pesticides were used as the model compounds for evaluating the microextraction. The parameters affecting the enrichment factor of the microextraction were investigated, including the funnel inner angle, solvent component, and microdrop volume, etc. With the optimized microextracting conditions, the enrichment factors of organochlorines and pyrethroids were 272–875 and 147–183, respectively. The detection limit was in the range of 1–12 ng/L (S/N = 3). The relative standard deviation (RSD) of peak height was less than 10.2% (n = 8). This proposed technique is simple, convenient, and efficient.