Background-subtraction of fast-scan cyclic staircase voltammetry at protein-modified carbon-fiber electrodes

Background-subtraction techniques were applied to the voltammetry of nicoti namide adenine dinucleotide (NADH) at protein-modified carbon-fiber microel ectrodes. The background currents at carbon-fiber electrodes were stable an d voltammetric scans immediately before or after the analyte were effective ly used for background subtraction. Digital step-potential waveforms were u sed to excite these carbon-fiber electrodes, where the resulting voltammetr ic analysis assessed the optimal switching and initial potentials and the e lectrochemical response time was determined. The initial potential was 0.0 V and the switching potential 1.1 V (versus Ag/AgCl) and the response time was approximately 300 ms. Some sensitivity to NADH was lost and voltammetri c prescans were required at protein-modified electrodes to obtain a stable baseline. Current versus time was assessed by the average current of the fa radaic region from each voltammogram and by differential current; the avera ge current minus the current from a non-faradaic potential range. Different ial current assessments discriminated against artifacts caused by pH (as hi gh as 1.0 pH unit) and ionic strength Flux (100 mM). These background-subtr action techniques allowed the faradaic information to be obtained quickly a nd conveniently while maximizing sensitivity and maintaining selectivity. ( C) 1998 Elsevier Science S.A. All rights reserved.