Square Wave Voltammetric and Ion Selective Potentiometric Strategies for Spiramycin Determination in Pharmaceutical Formulations

Herein, two electrochemical methods are suggested for the determination of spiramycin (SPI) in pharmaceutical finished products. The first method is based on square wave voltammetric strategy (SWV) for the oxidation of SPI at a carbon paste electrode in a surfactant-containing electrolyte. Studying the cyclic voltammetry of SPI showed that the electrochemical oxidation process of SPI is irreversible with a peak current at 0.87 V in Britton- Robinson buffer (pH 9.0). Several important parameters including the influence of surfactants, the pH of the electrolyte and the rate of scan on the peak current were investigated. Under optimal experimental conditions, a linear response was obtained in the concentration range from 5 μM to 450 μM. The second method aims at the fabrication and characterization of a potentiometric homemade screen-printed electrode for the cost-effective determination of SPI. A Nernstian potentiometric response for SPI was achieved using potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as a lipophilic ion exchanger in a polymeric PVC membrane over the concentration range from 1×10-6 to 1×10-2 M. However, the effect of membrane composition with respect to the ion exchanger and the plasticizers on the potentiometric response was remarked. The proposed voltammetric and potentiometric methods were successfully applied for the determination of SPI in bulk powder, in pharmaceutical formulations and monitoring SPI in natural water without extraction or sample pre-treatment.