REACTIVATION OF AN IMMOBILIZED ENZYME REACTOR FOR THE DETERMINATION OF ACETYLCHOLINESTERASE INHIBITORS FLOW-INJECTION DETERMINATION OF PARAOXON

A stopped-flow/flow-injection procedure is proposed for the spectrophotometric determination of paraoxon based on the inhibition of immobilized acetylcholinesterase. The irreversibly inhibited enzyme is reactivated with 1,1'-trimethylene-bis(4-formylpyridinium bromide) dioxime. The proposed procedure has a detection limit of 4 x 10(-9) M, a linear calibration range of 9 x 10(-9)-5 x 10(-7) M, a R.S.D. of 1.6% (n = 10) at 5.0 X 10(-8) M and a sample throughput frequency of 10 h(-1). The enzyme reactor can be used for more than one thousand inhibition-reactivation cycles.