Comparison of Pt and Ni foil electrodes for amperometric sensing of ascorbic acid

Metal foils made of Pt and Ni show amperometric responses to ascorbic acid (H2A). This study compares the sensitivity of a Pt foil electrode to that of a Ni foil electrode. Both electrodes were highly sensitive to H2A; the Pt foil electrode was more sensitive at an applied potential of 0.2 V vs. Ag/AgCl in KOH than it was in H2SO4 and Na2SO4. These electrodes showed excellent selectivity for H2A over glucose, fructose, sucrose, tartaric acid, citric acid, oxalic acid, and sodium benzoate. Both electrodes displayed rapid responses and good linearity levels in the range from 0.57 to 5.68 mM. Compared to the Ni foil electrode, the Pt foil electrode possessed better long-term stability, because it maintained 99% of its initial sensitivity for more than 67 days.