An enzyme based biosensor for the direct determination of diisopropyl fluorophosphate Original Research Article

The ability of organophosphate hydrolase (OPH, EC 3.1.8.1) from Pseudomonas diminuta to hydrolyze diisopropyl fluorophosphate (DFP) was used to develop a biosensor for the direct determination of DFP. A fluoride sensitive ion-selective electrode was exploited as the physical transducer for a batch-mode biosensor, and OPH enzyme immobilized on silica gel was used as a biological recognition element. The correlation between DFP concentration and hydrolyzed fluoride extended over a concentration range of 2.5×10−5–5×10−3 M. The influence of MeOH on DFP hydrolysis by immobilized OPH was greatly reduced from that of the soluble enzyme, and the effect of paraoxon on DFP detection in mixed samples was investigated.