Ultratrace determination of adenine in the presence of copper by adsorptive stripping voltammetry

An electrochemical stripping procedure for ultra-trace measurements of adenine is described based on the adsorption of the adenine–copper complex on a static mercury drop electrode. Cyclic voltammetry was used to characterize the interfacial and redox behavior. Optimum experimental conditions were found when using a 0.005 M NaOH solution containing 0.4 ppm of copper, an accumulation potential of −0.30 V, a scan rate of 100 mV s−1 and a linear scan mode. There is a linear response to adenine concentration in the range of 0.1–1.0 ppb and the detection limit for 6 min accumulation time was of 4.0 ppt (3.0×10−11 M). Proper conditions for measuring the adenine in presence of guanine, thymine and cytosine were also investigated. The method was applied for the determination of adenine in a sample of single-stranded calf thymus DNA.