A novel PVC membrane selective electrode for the determination of sodium nitroprusside in pharmaceutical preparations

A novel PVC membrane electrode, selective for the determination of the antihypertensive medication sodium nitroprusside (SNP) based on cetylpyridinium-nitroprusside ion pair association as an electroactive material is described. The electrode shows a linear response for nitroprusside NP) ion over the concentration range of 3 x 10(-5) -1 X 10(-2) M with lower detection limit of 2 x 10(-5) M at 25degreesC. The electrode possesses a Nernstian slope of -27.0 +/- 1.0 mV/decade and a fast potential response of 45 s, which is almost constant over a pH range of 2.0-10.0. Selectivity coefficient data for some common ions show negligible interference. An average recovery of 99.7% with relative standard deviation of 0.76% has been achieved for the determination of SNP in Nipride. The electrode has been utilized as an end point indicator electrode for the determination of SNP using potentiometric titration.