Electrochemically Reduced Carboxyl Graphene Modified Electrode for Simultaneous Determination of Guanine and Adenine

An electrochemically reduced carboxyl graphene modified glassy carbon electrode (ERCGr/GCE) was prepared from a carboxyl graphene modified glassy carbon electrode (CGr/GCE) and employed for the simultaneous determination of guanine and adenine. The ERCGr/GCE showed an enhanced voltammetric response toward the oxidation of guanine and adenine compared with the CGr/GCE because the conductivity and electrochemical active surface area increased during the reduction process. The voltammetric peak current was linearly dependent on guanine and adenine concentration over the ranges of 0.5–10 and 2.5–50 µmol L−1, respectively. The detection limits were 0.15 µmol L−1 for guanine and 0.10 µmol L−1 for adenine in 50 µmol L−1 phosphate buffer at pH 6.86. Determination of guanine and adenine in thermally denatured herring sperm DNA showed that the ratio of guanine/adenine was 0.758 demonstrating practical application of the ERCGr/GCE.