AFFINITY ENZYMOMETRIC ASSAY FOR DETECTION OF ORGANOPHOSPHORUS COMPOUNDS

A new method for the detection of organophosphorus compounds has been developed. Organophosphorus compounds are recognized by binding of an excess of bienzyme conjugate (BEG) built up by butyrylcholinesterase a s a receptor and horseradish peroxidase as the signal generating and a mplifier element. The separation of the analyte-free bienzyme conjugat e from the analyte-loaded bienzyme conjugate is performed on an affini ty support formed by a Langmuir film containing an amphiphilic paraoxo n derivative (B-1). The analyte-free bienzyme conjugate binds irrevers ibly to the affinity support. Bienzyme conjugate with bound analyte is prevented from binding to the B-1 film modified support and can thus be detected in the eluate solution by the horseradish peroxidase activ ity. This activity is directly proportional to the concentration of or ganophosphorous compounds. The assay procedure was developed for both the steady-state and the flow-injection mode. In both cases the lower limit of detection was about 1 pM for diisopropylflurophosphate. (C) 1 997 Elsevier Science B.V.