Determination of Isocarbophos,Phosemet,Methyl-parathion,Phosalone Residues in Tea Sample by High Performance Liquid Chromatography

A method has been developed for quantitative determination of isocarbophos,phosemet,methyl-parathion,and phosalone residues in tea samples.The pesticide residues were extracted from tea samples with mixture of ethyl acetate and n-hexane(1◇1,by vol.) at 45℃.The extracts were then treated with a cartridge packed with active carbon and 10 mL eluant of ethyl acetate and n-hexane(6◇1).The 4 organophosphorus pesticides were separated with Eclipse XDB-C8 column and detected with diode array detector at programmed wavelength.The recoveries for added standard were 89.0%~108.0%.The relative standard deviations were 1.89%~5.96%(1.0 μg/mL,n=5).The limits of quantitative determination(3σ) in dry tea samples were 9.82,7.88,2.19 and 0.72 μg/kg for isocarbophos,phosemet,methyl-parathion and phosalone,respectively.