Catalytic cathodic stripping voltammetry of 6-mercaptopurine-9-D-riboside in the presence of nickel ion

Differential pulse cathodic stripping voltammetry of 6-mercaptopurin-9-D-ribose (6-MPR) at a HMDE was investigated at pH about 7 in the presence of nickel ion. According to the value of the accumulation potential, 6-MPR was pre-concentrated as either a mercury compound or an adsorbed nickel complex. During the subsequent cathodic scan 6-MPR does catalyze the reduction of nickel ion giving a peak at about -0.8 V vs. SCE. This peak enables the determination of 6-MPR at concentrations down to 1 nM with no substantial interference from the heavy metal ions, chloride, alkali metals and complexing agents and only moderate interference by thiols and surface-active compounds. The best sensitivity and reproducibility are achieved under the following conditions: pH 7.5 (phosphate-acetate buffer) ; Ni2+, 1 mM; Eacc, -0.3 V; tacc, 1 min; scan speed, 20 mV/min.; pulse interval, 0.1 sec.