Aminoguanidine (AG), as a group of nucleophilic hydrazine compounds, has different pharmacological activities, like reducing the pathological consequence of diabetes. Here, the electrochemical oxidation behavior of aminoguanidine was examined, directly at bare graphite electrode and indirectly, with theophylline hybrid polymer and copper oxide nanoparticles, using cyclic voltammetry (CV) and square wave voltammetry (SWV). The impact of pH, buffer type, time, and concentration were studied in the two methods. Two oxidation peaks were found at (0.773 V , 1.15 V) vs. Ag/AgCl in acetate buffer (0.1 M, pH 4.5) and (0.8 V , 1.1 V) vs. Ag/AgCl in phosphate buffer (0.1 M, pH 7.0). At graphite bare electrode (GCE), the optimal result was achieved when the phosphate buffer was used, changing the linear range for the detection of aminoguanidine at bare electrode from 299.1 to 990 µM with R2 of 0.992 and standard deviation of 33.5 µM. At modified graphite electrode with theophylline hybrid polymer and copper oxide nanoparticles (GCE-poly TP/CuO-NPs), a much wider range was obtained for AG, at 9.9 to 610.316 µM with R2 =0.990 the limit of detection of 6.34 µM, and SD of 0.089 µM.
Finally, the preparation of modified graphite electrode with nanoparticles (GCE-poly TP/CuO NPs) showed good stability, persisting for more than 2 weeks, and showing a potential to be used as a drug sensor.