Electrochemical sensors for direct potentiometric determination of Voriconazole in pharmaceutical dosage forms and biological fluids

Abstract

The compositions and general performance characteristics of four polyvinyl chloride (PVC) membrane sensors respective to Voriconazole (VR) were described. Two of these sensors are based on the use of ion association complexes of VR with phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) as novel electroactive materials dispersed ino-nitrophenyloctyl ether (o-NPOE) plasticizer on glass assemblies. The third sensor is a coated wire type and based on the ion association incorporation of the VR with tetraphenylborate (TPB). The forth sensor is a graphite electrode type based on ion association with silicotungstic acid (STA). The developed sensors were used for the determination of VR in pure form in its pharmaceutical formulations and in biological fluids. The sensors displayed Nernstain response 57.56 ± 0.16, 58.45 ± 0.54, 56.17 ± 0.28 and 57.09 ± 0.74 mV at 25oC, over linear concentration ranges from 9.0x10-7 to 1.0x10-2, 1.0x10-6 to 1.0x10-2, 1.0x10-6 to 1.0x10-2 and 5.0x10-6 to 1.0x10-2 molL-1 for the four mentioned sensors, respectively. The pH does not affect the sensor performances within the pH range of 3 to 8. Acceptable selectivity was obtained for VR against many inorganic cations, sugars and amino acids. Statistical student’s t-test and F test showed insignificant systematic error between proposed and reported methods. Key words: Voriconazole, potentiometry, ion-selective electrode, graphite sensors, pharmaceutical formulations, biological fluids.