Voltammetric determination of ascorbic acid by using a disposable screen printed electrode modified with Cu(OH)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) 2 nanorods (NRs). The NRs were synthesized by a wet chemical process which involves sequential addition of NH 3 and NaOH to CuSO 4 solution. NR formation was confirmed by thermogravimetric, spectroscopic, microscopic, and diffraction studies. The Cu(OH) 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 mΜ AA concentration range. Response to AA is free from interference by urea, glucose, uric acid, dopamine, metal ions such as Fe 2+ , Zn 2+ and Ni 2+ , NaCl, KCl and ethanol. It was applied to the determination of AA in a vitamin C tablet and in urine. Graphical abstract A disposable non-enzymatic sensor for ascorbic acid was fabricated using Cu(OH) 2 nanorods. The assay is based on the chemical reduction of Cu(II) by AA followed by an electrochemical oxidation of Cu(I). The sensor electrode showed excellent linearity (0.0125–10 mM), sensitivity (268 μA/mM/cm 2 ) and selectivity.