Electrochemical detection of guanosine-5'-triphosphate with a pyridinium-based carbon ionic liquid electrode

A new carbon ionic liquid electrode was constructed by mixing graphite powder, 1-(3-chloro-2-hydroxypropyl)pyridinium tetrafluoroborate, and liquid paraffin together. The electrode showed strong electrocatalytic activity in the oxidation of guanosine-5'-triphosphate (5'-GTP). A single well-defined irreversible oxidation peak of 5'-GTP appeared in the voltammogram measured using the traditional carbon paste electrode, and the electrochemical response was greatly enhanced on the new electrode, which was due to the presence of highly conductive ionic liquid in the electrode. The electrochemical parameters of 5'-GTP on the carbon ionic liquid electrode were calculated: the electron transfer coefficient (alpha) was 0.29, the electron transfer number (n) was 1.91, the apparent heterogeneous electron transfer rate constant (k (s)) was 7.46 x 10(-8) s(-1), and the surface coverage (D"(T)) was 9.71 x 10(-10) mol cm(-2). Under the optimal conditions, the plot of oxidation peak current versus 5'-GTP concentration was linear over the range from 0.80 to 400.0 mu M with a detection limit of 0.026 mu M (3 sigma). The proposed method showed good selectivity in the detection of 5'-GTP without interference from coexisting substances and was further applied to the determination of artificial samples with satisfactory results.