Investigations of platinized and rhodinized carbon electrodes for use in glucose sensors

Abstract

Graphite electrodes were modified by the electrodeposition of either platinum or rhodium, using cyclic voltammetry. Following only brief periods of treatment. platinized carbon electrodes were able to directly oxidize glucose at a potential of 1350 niV (vs. Ag/AgCl). By narrowing both the potential range of deposition (-450 to -500 mV) and qcling period ( S O seconds at a scan rate of 10 mL' s-I), the effects of direct glucose oxidation could be significantly reduced. Detection of H 2 0 1 at 1-400 m\. was possible: glucose enzyme electrodes were constructed, with glucose oxidase immobilized in hydroxyethylcellulose, and operated at this potential. These sensors had a linear range of 0.1 to 25 my1 glucose and a slope of 8 nA/rn,l/I. Other electrodes were prepared by the electrodeposition of rhodium. These base electrodes proved to be insensitive to glucose and produced higher currents (compared to low platinum electrodes) to H 2 0 1 . Glucose sensors were constructed using rhodinized electrodes. Again operating at 1-400 m\'. these sensors had a linear range from 0.1 to 20 mhl and a slope of 21 rui/mlZiI glucose.

Effects of polymerization potential on the permselectivity of poly(o-phenylenediamine) coatings deposited on Pt–Ir electrodes for biosensor applications

“…The use of 0.7 V for H 2 O 2 detection at Pt electrodes grew historically, probably because lower H 2 O 2 sensitivities are sometimes observed at lower applied potentials for high H 2 O 2 concentrations, due to the catalytic nature of this electrooxidation [97]. For concentrations of H 2 O 2 normally encountered in biosensor applications, and certainly up to 1 mM H 2 O 2 , a plateau is observed in the CV for H 2 O 2 in neutral media by 0.4 V versus SCE [31,55], and these lower potentials are now being exploited for H 2 O 2 detection in some biosensor applications [30,[98][99][100]. A separate set of Pt/PPD 400 electrodes (n = 4) were therefore calibrated at both 0.4 V and 0.7 V versus SCE.…”

Organic phase immunosensors

“…HRP activity was measured using hexacyanoferrate (II/III) mediator at bare carbon electrodes (-20mV vs. Ag/AgCl) using hydrogen peroxide as substrate. GOX activity was measured at a rhodinised carbon electrode (+350 mV vs. Ag/AgCl), a suitable surface for the mediator-free oxidation of the enzymatic reaction product, hydrogen peroxide [46][47][48].…”

Effect of L-Aspartate Concentration on the Response of the Amperometric L-Glutamate Sensor for the Measurement of L-Glutamate and Aspartate Aminotransferase Activity in Serum

“…The deposition of palladium on the electrode surface provides a very porous structure consisting of aggregates of fine palladium particles. This results in a significant increase in the electrode surface area, which leads to an increase in surface activity for the measurement of the hydrogen peroxide liberated from enzymatic reactions (White et al 1994;Newman et al 1995;Chi and Dong 1993;Johnston et al 1995). Second, the substrate must diffuse quickly through the thin layer to undergo the enzymatic reaction.…”