This paper reports on an experimental study of the ability to use ascorbic acid as a reducing agent for a clozapine (CLZ) biosensor based on redox cycling electrochemistry. Ascorbic acid, which is naturally present in the blood serum, was related to the current reducing mediator, hexaammineruthenium(III) (Ru). The performance of these two candidate compounds was compared using cyclic voltammetry in the range of −0.4 to 0.7 V at scan rates of 10 mV/s. Results from bare gold electrodes indicate an electrochemical interference on the CLZ signal in the presence of ascorbic acid but no interference in the presence of Ru. Ascorbic acid was further integrated in an electrochemical biosensor comprised of gold electrodes modified with electrodeposited chitosan hydrogel and grafted catechol moieties. This modification improves CLZ sensing by amplifying its electrochemical signal by a factor of nine, compared to bare electrodes. When measured with the modified electrodes, neither ascorbic acid nor Ru affect the performance of the CLZ biosensor. Ru demonstrated a 1.5 times higher amplification of the CLZ peak current signal compared to that of ascorbic acid.
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