Chemically modified carbon paste sensor for the potentiometric determination of carvedilol in pharmaceutical and biological media

• The sensor has wide linear range and very low detection limit.
• The proposed sensor has very high selectivity towards carvedilol.
• The sensor has fast response time and also long life time.
• The sensor can determine carvedilol in pharmaceutical, blood serum and urine samples.
• The sensor is the first reported potentiometric carbon paste sensor for carvedilol.

The construction and performance characteristics of a novel potentiometric carbon paste electrode based on incorporation of the ion-association complex of the carvedilol-phosphotungstate were studied. The electrode exhibited Nernstian slope of 58.7 mV/decade to carvedilol over a wide concentration range from 3.0 × 10−7 to 1.0 × 10−3 M with low detection limit of 1.5 × 10−7 M. The proposed sensor manifested advantages of fast response, long life time, and most importantly, good selectivities for carvedilol relative to a wide variety of common foreign inorganic cations, biological species and other β-blockers. The advantages of the new sensor were compared to the characteristics of previously reported traditional liquid inner contact PVC membrane electrode. The sensor was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of carvedilol in carvedilol tablet, blood serum and urine samples. The inclusion complex formation between α- and β-cyclodextrin and carvedilol was studied potentiometrically by the proposed sensor and formation constant of the inclusion complexes were calculated.