Methylated Azopyridine as a New Electron Transfer Mediator for the Electrocatalytic Oxidation of NADH

Abstract Carbon ionic liquid electrode (CILE) has been modified with a new synthesized mediator i.e. N , N′ ‐dimethyl‐4,4′‐azopyridinium hexafluorophosphate (MAZPHP) via sol process and the electron transfer mediating characteristics of this mediator has been evaluated. 4,4′‐Azopyridine (AZP) did not show any electrocatalytic activity toward the selected probe, NADH, while its synthesized methylated derivative, MAZPHP, is a very efficient mediator for the electrocatalytic NADH oxidation. Cyclic voltammetry of MAZPHP/Sol/CILE exhibited a pair of reversible peaks corresponding to incorporated mediator with a formal potential of about 221 mV vs. Ag/AgCl. MAZPHP/Sol/CILE is free from fouling effects by the oxidation products of NADH which generally give hindrance to amperometric detection of NADH. Using amperometric technique, NADH can be determined in the range of 1.0×10 −5 M to 1.4×10 −3 M with a detection limit of 2.0×10 −6 M.