ELECTROCATALYTIC OXIDATION AND FLOW DETECTION OF NAD(P)H AT A HISTIDINE MODIFIED SILVER ELECTRODE

L-Histidine, a biologically important amino acid, has been modified on to the silver electrode through covalent bonding. The coenzyme dihydro nicotinamide adenine dinucleotide (NAD(P)H) was electrocatalytically o xidized to NAD(P)(+) at a L-histidine modified silver electrode (His/A g). The electrochemical processes at the His/Ag electrode were investi gated by using UV-visible spectroelectrochemistry in detail. Amperomet ric determination of NAD(P)H, at a potential of 0.25V (SCE), gave a li near response in the range of 1 x 10(-7)similar to 2x10(-5) mol/L with a detection limit of 0.05 mu mol/L. The His/Ag electrode has been use d in a FIA system with satisfactory results. Meanwhile, other proteins and chemicals present in samples do not interfere in the assay.