Abstract.An electrochemical anodic stripping proce-dure for ultra-trace assay of xanthine in Cu 2þ solution at a glassy carbon electrode (GCE) is described. Cyclic voltammetry was used to characterize the nature of the process taking place at the GCE. The anodic stripping response in the presence of Cu 2þ , at 150 mV (peak I) and 600 mV (peak II), is evaluated with respect to various experimental and instrumental conditions. Voltammetric studies show that the mechanism of the overall reaction is similar to that of the oxidation of purine derivatives at a pyrolytic graphite electrode. It is found that the copper metal deposited onto the GCE was oxidized to Cu þ at around 180 mVvs. Ag=AgCl and the generated Cu þ reacted with xanthine to accumulate on the GCE as an insoluble compound. The Cu þ -xanthine compound accumulated on the GCE was redissolved by the oxidation of Cu þ to Cu 2þ at ca. 150 mV, and the concentration of xanthine in the vicin-ity of the GCE increased. The results enabled us to use the measurement of the oxidation peak current as the basis of a simple, accurate and rapid method of deter-mining xanthine within a concentration range of 19.9 to 166 nM for peak (I) and 0.24 to 17.2mM for peak (II). Promising results were obtained for xanthine determination by using an external mixing step prior to stripping measurements, which yielded a detection limit of 0.138mgL 1 (9.110 10 M) xanthine. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered