New Conductometric Titration Methods for Determination of Diphenhydramine Hydrochloride Using Sodium Tetraphenylborate and Cetylpyridinium Bromide

Sodium tetraphenylborate (TPB) and cetylpyridinium bromide (CPB) were used as titrant for the conductometric determination of diphenhydramine hydrochloride (DPH) drug through ion association complex formation and then the conductance of the solution is measured as a function of the volume of titrant. The effect of the solvent, reagent concentration, temperature and molar combining ratio of the formed ion-associates were studied and evaluated. The suggested method was applied for the determination of diphenhydramine hydrochloride in pure form and pharmaceutical preparations. The described procedures allowed the determination of the studied drug in bi-distilled water in the range of 0.75–16 mg. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method was indicated by excellent recovery and the precision supported by the low relative standard deviation <1%. The sensitivity of the proposed method was discussed and the results were compared with the potentiometric pharmacopoeial method. The proposed procedure was simple, precise and low cost and can be applied for the routine measurements of the cited drug.