Preparation and Potentiometric Study for Promethazine Hydrochloride

Electrodes for the determination of promethazine hydrochloride based on PVC membrane were prepared based on the use of ion pair (promethazine-phosphotungstic acid) with the following plasticizers: Di-butyl phosphate (DBP), Tri-butyl phosphate (TBP), O-nitrophenyloctyl ether (ONPOE), and Di-butyl phthalate (DBPH). The properties of these electrodes were studied, including: slope, correlation coefficient, concentration range, detection limit, pH effect, and life time. The statistical treatments were applied for the results that include: relative standard deviation (RSD), relative error (RE), mean error, confidence limit for concentration, and confidence limit for potential. The electrodes (A,B and C) based on DBP, TBP and ONPOE respectively, gave a same linear range from 1x10-1 to 1x10-4 M but for electrode D based on DBPH gave the linear range from 1x10-1 to 5x10-4 M. The slopes are (40.58, 39.82, 51.52 and 56.17) mV/decade, with the correlation coefficients are (0.9984, 0.9988, 0.9991 and 0.9993), and the limit of detection 3.5x10-5, 5x10-5, 5.5x10-4 and 2x10-4 M respectively.