Polypyrrole-coated rubber foam sorbent for extraction of fipronil and fipronil sulfone in tea

A polypyrrole-coated rubber foam sorbent with a steel wire insert was developed for the magnetic solid phase extraction of fipronil and fipronil sulfone from tea samples for analysis by a gas chromatography-electron capture detector. Under the optimum conditions, the method linear ranges were 0.05-100 & mu;g/L for fipronil and 0.01-100 & mu;g/L for fipronil sulfone. The limits of detection were 0.01 and 0.005 & mu;g/L while limits of quantitation were 0.05 and 0.01 & mu;g/L for fipronil and fipronil sulfone, respectively. The preparation procedure of the developed sorbent exhibited good reproducibility with a relative standard deviation in the range of 1.9%-2.4% spiked at 50 & mu;g/L. Good precision was obtained with a relative standard deviation below 6.7% in four concentrations ranging from 0.0 to 50 & mu;g/L. Fipronil sulfone was detected in two tea samples at concentrations of 1.79 & PLUSMN; 0.05 and 2.64 & PLUSMN; 0.03 & mu;g/L with recoveries ranging from 80.4 & PLUSMN; 1.5% to 110.0 & PLUSMN; 2.0%. Thus, the developed sorbent exhibited high extraction efficiency with good selectivity towards the target analytes in real samples.