Specific Ion Effects on the Mediated Oxidation of NADH

The electrochemical mediated oxidation of dihydronicotinamide adenine dinucleotide (NADH) by 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was examined in a range of electrolytes. Changes in the Faradaic response were observed that were dependent on the nature of the salt used. In the presence of 200 mM chloride salts, the Faradaic response followed the trend Na⁺>K⁺>Li⁺>Cs⁺>Gnd⁺ while in the presence of 200 mM sodium salts, the trend Cl⁻>Br⁻>F⁻>ClO₄ ⁻>SCN⁻ was observed. The observed trends varied when the concentration of the ions was altered. The effect of the cation also changed when the counterion was changed, indicating that specific ion pair effects were present. The results indicate that the nature of the electrolyte alters the Faradaic response.