KINETIC ENZYMATIC DETERMINATION OF CHLORPYRIPHOS IN APPLES

A spectrofluorimetric method for the determination of chlorpyriphos in apples, based on the inhibition of the acetylcholinesterase enzyme (A ChE), has been established. The method employs a non-fluorescent synth etic enzyme substrate (Indoxyl acetate), which is hydrolyzed by the en zyme to yield a highly fluorescent product. In presence of the inhibit or, the rate of formation of this fluorescent product is lowered The r ate of change in the fluorescence is measured Delta F/Delta t. (lambda (ex) = 395 nm; lambda(em) = 470 nm). The simple spectrofluorimetric me thod described for the determination of chlorpyriphos in apple has a l imit of detection of 13.68 mu M with relative standard deviation of 7. 1 %. The method was applied to chlorpyriphos added (28.5 and 57 mu M) to apples with recoveries ranged between 107% and 91%.