Electrochemical Detection of Ribonucleotides At A Carbon Paste Electrode Containing Cobalt Phthalocyanine

Abstract

Chemically modified electrodes (CMEs) prepared by mixing cobalt phthalocyanine into carbon paste were shown to be able to carry out the electrocatalytic oxidation of nucleic acid species. the oxidation, which occurred at +0.4-0.5 V vs. Ag/AgC1 in 0.15 M NaOH, was observed only for ribose-containing compounds such as the ribonucleosides cytidine, uridine, adenosine, and guanine but not for deoxyribonucleosides such as thymidine or for the purine and pyrimidine bases by themselves. When used for electrochemical detection of the ribonucleosides following liquid chromatography, limits of detection were at the nmol level, with linear response extending at least two orders of magnitude higher. the stability of the CME response was such that 20-30 injections over one hour showed virtually no decrease in peak current and a relative standard deviation of only 2.5%. the detection limits seen with the CMEs were rougnly comparable to those seen for absorption detection at 280 nm, but the selectivity of the CMEs was much narrower in practice.