▎ 摘　　要

A Fe3O4-graphene oxide hybrid composite (Fe3O4- GO) was synthesized and used to construct a novel electrochemical sensor for the simultaneous detection of adenine and guanine. The Fe3O4-GO based electrochemical sensor exhibits linear ranges of 0.05-25 mu M and 0.05-25 mu M with detection limits of 4 nM and 3 nM for adenine and guanine, respectively. This method was applied in the determination of guanine and adenine in many samples with satisfying results. The value of (G+C)/(A+T) in DNA was calculated to be 0.7536. The sensor exhibits some advantages, such as rapidity, good reproducibility and long-term stability.