HPLC Determination of Residual Amounts of Clofentezine in Apples

HPLC was applied to the determination of residual clofentezine in apples.Sample of apple was mixed and pulpfied with acetone,and centrifuged to dissolve clofentezine in the solvent.The supernatant solution was collected and extracted with dichloromethane after addition of 150 mL of 20 g·L-1 Na2SO4 solution.The extract was evaporated to dryness at 40 ℃,and the residue was taken up with methanol-dichloromethane(1+99) mixture.The solution was then purified by passing through the Sep-PakVac Amino micro-column and eluted with methanol-dichloromethane(1+99) mixed solvent.The eluate was evaporated to dryness by blowing with nitrogen,and dissolved with a definite volume of the mixed solvent eluant.The solution obtained was used for HPLC determination.Agilent Zorbax SB C18 stainless steel column was used as chromatographic column,and methanol-water(75+25 by vol.) solution was used as mobile phase in the HPLC analysis with photodiode array detection at 273 nm.Linear relationship between values of peak area and concentration of the insecticide was found in the range of 0.35-14 mg·L-1 with determination limit(10S/N) of 0.05 mg·kg-1.Recovery was tested at 3 concentration levels,giving values of recovery over the range 90.0%-92.0% and RSD′s(n=6) over the range 2.1%-3.8%.