Electrochemical sensor for the simultaneous voltammetric determination of adenosine and adenine

Electrochemical method based on voltammetry using bare and single walled carbon nanotubes (SWNT) modified edge plane pyrolytic graphite electrode (EPPGE) is proposed for the simultaneous determination of adenosine and adenine in phosphate buffer medium of pH 7.2. The oxidation peak current of both the analytes increases significantly along with the negative shift of peak potentials using SWNT/EPPGE as compared to bare EPPGE. The modified electrode exhibits enhanced electrocatalytic properties towards adenosine and adenine with a peak potential of ~ 1190 mV and ~ 856 mV, respectively. Oxidation of both the compounds occurs in a pH-dependent process, and the electrode reaction follows diffusion controlled pathway. The concentration versus peak current plots are linear for both the analytes. The detection limit (3σ/slope) observed for adenine and adenosine are 1.1 and 2.9 μM, respectively. The developed protocol has been implemented for the simultaneous determination of adenosine and adenine in human urine samples of normal subjects with good results.