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BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. 1. POTENTIOMETRIC ENZYME ELECTRODE. (R823663)
Citation:
Mulchandani, P., A. Mulchandani, I. Kaneva, AND W. Chen. BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. 1. POTENTIOMETRIC ENZYME ELECTRODE. (R823663). Analytical Chemistry. American Chemical Society, Washington, DC, 14:77-85, (1999).
Description:
A potentiometric enzyme electrode for the direct measurement of organophosphate (OP)
nerve agents was developed. The basic element of this enzyme electrode was a pH electrode
modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking
OPH with bovine serum albumin (BSA) and glutaraldehyde. OPH catalyses the hydrolysis of
organophosphorus pesticides to release protons, the concentration of which is proportional to the
amount of hydrolysed substrate. The sensor signal and response time was optimized with respect to
the buffer pH, ionic concentration of buffer, temperature, and units of OPH immobilized using
paraoxon as substrate. The best sensitivity and response time were obtained using a sensor
constructed with 500 IU of OPH and operating in pH 8.5, 1 mM HEPES buffer. Using these
conditions, the biosensor was used to measure as low as 2 mu M of paraoxon, ethyl parathion,
methyl parathion and diazinon. The biosensor was completely stable for at least one month when
stored in pH 8.5, 1 mM HEPES + 100 mM NaCl buffer at 4 degrees C. (C) 1999 Elsevier Science
S.A. All rights reserved. (56 References)