P. Calvo-marzal et al., Electroanalytical determination of acid phosphatase activity by monitoringp-nitrophenol, ANALYT CHIM, 441(2), 2001, pp. 207-214
The development of a modified electrode for the selective determination of
p-nitrophenol (PNP) to be applied in the determination of the enzymatic act
ivity (EA) of acid phosphatase using p-nitrophenylphosphate (PNPP) as subst
rate is described. Elimination of the interference of PNPP was made by cove
ring the electrode surface using 25 mul of a 5% (m/v) Nafion (R) solution.
In comparison to the glassy carbon (GC) electrode without modification, the
presence of the membrane promoted a reduction in the sensitivity and an in
crease in the detection limit for the determination of PNP, in addition to
a decrease of the electron transfer constant. The GC electrode covered with
a Nafion (R) membrane showed a linear response range between 20 and 230 mu
mol l(-1) for PNP, adjusted by the equation I-p = 0.157 + 0.0089 [PNP], fo
r N = 22 with a correlation coefficient of 0.9984. This electrode was used
for the determination of the EA of acid phosphatase from castor bean seeds
and an activity of 38.40 U mg(-1) was found. (C) 2001 Elsevier Science B.V.
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