Didanosine determination in diluted alkaline electrolyte by adsorptive stripping voltammetry at the mercury film electrode

A stripping method for the determination of didanosine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of didanosine at thin-film mercury electrode followed by a linear cyclic scan voltammetry measurement of the surface species. Optimum experimental conditions include a NaOH solution of 2.0′10-3 mol L-1 (supporting electrolyte), an accumulation potential of -0.20 V, and a scan rate of 100 mV s-1. The response of didanosine is linear over the concentration range 0.01 – 0.10 ppm. For an accumulation time of 7 minutes, the detection limit was found to be 0.43 ppb (1.0′10-9 mol L-1). The more convenient relation to measuring the didanosine in presence of the metals ions, efavirenz, acyclovir, nevirapine, indinavir, nelfinavir, saquinavir, lamivudine and zidovudine were also investigated. The utility of the method is demonstrated by the presence of didanosine together with hypoxanthine, ATP or DNA