PVC membrane, coated-wire, and carbon-paste electrodes for potentiometric determination of vardenafil hydrochloride in tablet formulations and urine samples

Abstract

Comparative study was made between three designs of vardenafil ion (Vr)-selective electrodes: a poly vinyl chloride (PVC) membrane (liquid inner contact) called electrode A, copper-coated (solid contact) called electrode B and a modified carbon paste electrode (CPE) called electrode C based on vardenafil - tetraphenylborate (Vr-TPB) as ion-exchanger complex. Electrode A has a linear dynamic range from 4.5X10-6 – 1.0X10-2 ​M, with a Nernstian slope of 51.8 mV/ decade and a detection limit of 1.6X10-6 ​M. Electrode B shows linearity over the concentration range from 8.0X10-6 - 1.0X10-2, with a Nernstian slope of 55.8 ​mV/decade and a limit of detection of 4.3X10-6 ​M. Electrode C exhibits linearity over the concentration range from 8.0X10-6 - 1.0X10-2 ​M, with a Nernstian slope of 61.3 mV/decade and a limit of detection of 4.0X10-6 ​M. These sensors exhibited a fast response time (about 2 ​s) and good stability. Selectivity coefficients, determined by modified separate solution method (MSSM) and separate solution method (SSM), showed high selectivity for vardenafil hydrochloride (VrCl) over a large number of inorganic cations, organic cations, sugars, urine components, and some common drug excipients. The proposed sensors were applied for determination of VrCl in tablets and in spiked urine samples using potentiometric determination and the calibration curve methods. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay. The CPE is more suitable for commercialization owing to its attractive properties.

Keywords

• Potentiometry
• Carbon paste electrode
• Vardenafil hydrochloride
• PVC electrode
• Coated wire electrode