S. Fennouh et al., INCREASED PARAOXON DETECTION WITH SOLVENTS USING ACETYLCHOLINESTERASEINACTIVATION MEASURED WITH A CHOLINE OXIDASE BIOSENSOR, Biosensors & bioelectronics, 12(2), 1997, pp. 97-104
Inactivation by paraoxon of free and immobilized acetylcholinesterase,
in the presence of various amounts of different organic solvents, and
with choline oxidase immobilized on an oxygen electrode was studied.
With acetylcholinesterase in solution it was found that 5% cyclohexane
enhances paraoxon detection when compared to the detection without so
lvent. In these conditions, as low as 10(-9) M paraoxon can be detecte
d. Free acetylcholinesterase was more sensitive to paraoxon than immob
ilized acetylcholinesterase, depending on the nature and concentration
of solvent (500-fold in the presence of 5% cyclohexane). The stabilit
y of the biosensor in continuous use and stored at room temperature wa
s at least 3-4 weeks with triton X100 and bovine serum albumin additio
n. The sensitivity of paraoxon detection with free acetylcholinesteras
e in the presence of 5% cyclohexane corresponds to 0.2 ppb paraoxon, 1
0-fold below the legal limit admitted in the European Economic Communi
ty. The same approach could be applied for detection of low amounts of
different organophosphorus or carbamate pesticides. (C) 1996 Elsevier
Science Limited