Abstract
Polyoxometalates (POM) are a class of inorganic compounds with various structures and remarkable electrical, magnetic and optical properties. Ion-pair complexes formed with some organic cations have high lipophilicity and they can be used as ionophores for PVC matrix membranes with active recognition function. The present study describes the construction and characterization of selective membrane sensors based on electroactive material incorporated in PVC matrix. They have been employed for the determination of ranitidine and nizatidine by using their complexes with silicotungstic acid as ionophores. The composition of the membrane has been optimized. The linear response range for both sensors was between 10-1-10-5M with quantification limits of 2.83·10-6M for ranitidine and 3.43·10-6M for nizatidine, and a response time shorter than 50 seconds. The new electrodes have been used for the potentiometrical determination of ranitidine and nizatidine in pharmaceutical products.
Keywords: polyoxometalates; polymer inclusion membranes; electrochemical sensor; ranitidine; nizatidine