The electrocatalytic oxidation of ascorbic acid
(AA) has been studied by p-aminophenol modified carbon
nanotubes paste electrode (APMCNTPE). Cyclic
voltammetry (CV) and chronoamperometry were used to
investigate the suitability of AP as a mediator for the electrocatalytic
oxidation of AA in aqueous solution. The oxidation
of AA occurs at a potential about 320 mV less
positive than with the unmodified carbon paste electrode at
pH 7.0. The catalytic reaction rate constant, k
was calculated
(2.257×10
3
M
−1
s
−1
h
) using chronoamperometry. The
differential pulsevoltammetric (DPV) peak currents of the
electrode increased linearly with the corresponding AA
concentration in the range of 2.0×10
−7
M – 1.2×10
M
with a detection limit of 8.0×10
−8
M. The influence of pH
and potential interfering substances on the determination of
AA were studied. Finally, the proposed method was also
examined as a selective, simple and precise electrochemical
sensor for the determination of AA in real
samples such as fruit juices and fresh vegetable juice.
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