Determination of 7 Pyrethroids Residues in Tea

A method for the simultaneous determination of residues of 7 pyrethroids - bifenthrin,fen- propathrin, cyhalothrin, permethrin, cypermethrin, fenvalerate and deltamethrin-in tea was established by gas chromatography. The pyrethroids in tea were expected by acetone - water(8: 1 by volume) so- lution, followed by n -hexane reextraction. After the extract was purified through a florisil column, the pyrethroids were analyzed by GC - ECD and quantified by external standard method. Recovery rates of the pyrethroids are more than 75%, minimum detectable quantities are less than 1.0 × 10 -8(w), wheras RSD of the method is in the range of 3.10% - 6.15%.