There are many reasons for modifying an electrode surface, including: 1) improvement of the limit of detection and sensitivity toward the analyte, 2) conversion of the analyte into an electrochemically detectable species, 3) protection of the electrode surface from poisoning, and 4) improvement of analyte selectivity. Often, modification procedures are long and complex, which preclude their use in an undergraduate instrumental analysis laboratory. This poster will show details of a simple modification of a glassy carbon electrode (GCE) with 3,4-dihydroxybenzaldehyde (DHB), which has been shown to operate as an efficient electrocatalyst for the oxidation of b-nicotinamide adenine dinucleotide (NADH). The use and response of the resulting modified GCE for the determination of NADH concentration at low applied potentials will also be discussed, as will the selectivity improvement for the NADH analyte in the presence of the electrocatalyzing DHB film. The same type of DHB-modified GCE can also be used in a continuous-flow system with amperometric detection of NADH.

This experiment can be used to highlight several key principles/topics in the field of electrochemistry such as: cyclic voltammetry, electrode modification, electropolymerization, electrocatalysis, analyte concentration/current relationships, analyte selectivity and its relationship to the limit of detection, continuous-flow analysis, coenzyme/enzyme/substrate reactions, and amperometry.