Estimation of amoxicillin in presence of high concentration of uric acid and other urinary metabolites using an unmodified pyrolytic graphite sensor

Voltammetric determination of amoxicillin (AMX) has been carried out using an unmodified edge plane pyrolytic graphite (EPPG) sensor. The peak corresponding to the oxidation of AMX was found close to ∼560 mV, both in cyclic as well as in square wave voltammetry. AMX has been quantified using square wave voltammetry in the linear concentration range of 5-500 μM at pH 7.2. Sensitivity and detection limit of 0.0742 μA μM^-1 and 0.84 μM was achieved respectively. The well separated peak of AMX, from the common metabolites present in urine, such as UA, xanthine and hypoxanthine, demonstrates the selective nature of the developed sensor. Also, no change in the peak current of AMX, in the presence of clavulanic acid and ampicillin (used commercially in combination with AMX), indicated the practical utility of the developed sensor in pharmaceutical industries. The analytical applicability of the sensor was checked by analyzing different pharmaceutical formulations and by quantification of AMX in the urine sample of the patients undergoing treatment with AMX. The results were further validated using HPLC and a comparison demonstrated the successful application of the proposed sensor for the fast, simple and selective analysis of AMX at pharmaceutical and medical fronts.