Preparation and Potentiometric Study of Promethazine Hydrochloride Selective Electrodes and Their Use in Determining Some Drugs

Authors: NABIL S. NASSORY, SHAHBAZ A. MAKI, BASHAER A. AL-PHALAHY

Abstract: Promethazine hydrochloride selective electrodes were constructed based on promethazine-phosphotun- gstic acid ion pair in PVC matrix membrane. The plasticizers used were di-butyl phosphate (DBP), tri-n-butyl phosphate (TBP), o-nitro phenyl octyl ether (ONPOE), and di-n-butyl phthalate (DBPH). The electrodes based on DBP, TBP, and ONPOE gave the same linear range between 1 x 10^{-4} and 1 x 10^{-1} M, while the one based on DBPH ranged between 5 x 10^{-4} and 1 x 10^{-1}M. The slopes for linear range ranged from 40 to 56 mV/decade with correlation coefficients lying between 0.9984 and 0.9993. The best detection limit was 2 x 10^{-5}M for the electrode based on DBPH. The standard deviation of potential drift ranged from \pm1 to \pm9 mV. The measurement interferences in the presence of Li^+, Na^+, K^+, Mg^{2+}, Ca^{2+}, Zn^{2+}, Fe^{3+}, Cr^{3+}, and Al^{3+} were studied using separate and match methods for selectivity coefficient determination. The pH and life time of the electrodes were also studied.

Keywords: Promathazine-HCl selective electrodes, phosphotungstic acid, promethazine determination

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