Voltammetric determination of ascorbic acid by using a disposable screen printed electrode modified with Cu.sub.2 nanorods

The authors describe a disposable non-enzymatic sensor for ascorbic acid (AA) that was obtained by modifying a screen printed electrode (SPE) with Cu(OH).sub.2 nanorods (NRs). The NRs were synthesized by a wet chemical process which involves sequential addition of NH.sub.3 and NaOH to CuSO.sub.4 solution. NR formation was confirmed by thermogravimetric, spectroscopic, microscopic, and diffraction studies. The Cu(OH).sub.2 NRs were mixed with carbon ink and printed onto an SPE. Electrochemical detection of AA was carried out at pH 7.4, at a typical voltage as low as 0 mV versus saturated calomel electrode with a scan rate of 100 mV/s, and is assumed to involve the chemical reduction of Cu(II) by AA followed by electrochemical oxidation of Cu(I). The sensor has a linear response in the 0.0125 to 10 m[Mu] AA concentration range. Response to AA is free from interference by urea, glucose, uric acid, dopamine, metal ions such as Fe.sup.2+, Zn.sup.2+ and Ni.sup.2+, NaCl, KCl and ethanol. It was applied to the determination of AA in a vitamin C tablet and in urine.