Polymeric membrane electrodes for selective determination of the central nervous system acting drugs fluphenazine hydrochloride and nortriptyline hydrochloride Original Research Article

The construction and electrochemical response characteristics of poly(vinyl chloride) (PVC), membrane sensors for determination of fluphenazine hydrochloride and nortriptyline hydrochloride are described. The method is based on the formation of the ion-pair complexes between the two drugs cations and sodium tetraphenylborate (NaTPB) or tetrakis (4-chlorophenyl) borate (KtpClPB). Four poly(vinyl chloride) sensors were fabricated. For fluphenazine HCl sensors 1 and 3 were prepared using NaTPB and KtpClPB, respectively. For nortriptyline HCl sensors 2 and 4 were prepared using NaTPB and KtpClPB, respectively. They show linear responses for both drugs over the concentration ranges of 10−3–10−5, 10−2–10−5, 10−3–10−5 and 10−2–10−5 M with cationic slopes of 58.9, 52.5, 59.3 and 54.3 mV per concentration decade, for sensors 1–4, respectively. The direct potentiometric determination of fluphenazine and nortriptyline hydrochlorides in their pure forms using the proposed sensors gave recoveries of 98.8±0.9, 99.0±0.9, 98.7±0.8 and 99.4±0.8% for sensors 1–4, respectively. This is compared reasonably with the data obtained using the British Pharmacopoeial method (1993). Sensors 1–4 were also used for determination of both drugs in their pharmaceutical dosage forms and in the presence of their degradates. It is noteworthy to mention that tetrakis (4-chlorophenyl) borate affects significantly the life time of the fabricated sensors of both drugs.