SIMULTANEOUS DETERMINATION OF RESIDUAL AMOUNTS OF CHLORPYRIFOS CYPERMETHRIN AND FENVALERATE IN VEGETABLES BY GAS CHROMATOGRAPHY

Gas chromatography was applied to the simultaneous determination of 3 pesticides,i.e.chlorpyrifos,cypermethrin and fenvalerate,in vegetables,and HP-5 quartz capillary column(30 m×0.25 mm i.d.×0.25 μm) and electron capture detector(ECD) were used in the separation and detection.Chromatographic parameters were described in detail.It was found that better efficiency of extraction and higher recovery were obtained by using petroleum ether as extractant than by using mixed solvents as extractant;and that the efficiency of purification was quite satisfactory by the use of the floridin silicious clay.A mixed standard solution was prepared from primary standards of the 3 pesticides,and calibration curve for each of the 3 pesticides was prepared covering the concentration ranges of 0.02 to 0.20 mg·L~(-1).The correlation coefficients of these calibration curves were 0.999 for chlorpyrifos and cypermethrin,and 0.998 for fenvalerate;and their detection limits were 0.001,0.002 and 0.002 mg·kg~(-1) respectively.Recovery tests by addition of standard solutions at 3 concentration levels on the base of blank vegetable samples gave results in the range of 85.3% to 93.1%,and(RSD′s) obtained were in the range of 0.13% to 2.16%.