Construction of ion-selective electrodes for chlorpromazine, amitriptyline, propantheline and meperidine: analytical study and application to pharmaceutical analysis

Abstract

Liquid-membrane ion-selective electrodes that respond to the cationic forms of chlorpromazine, amitriptyline and meperidine and to the quaternary ammonium compound propantheline are described. The liquid ion exchangers used were the salts of chlorpromazine or amitriptyline with eosin and tetraphenylborate in p-nitrocumene, propantheline with tetraphenylborate in 2-nitrotoluene and meperidine with tetrakis(m-chlorophenyl)borate in p-nitrocumene. The electrodes exhibited near-Nernstian response in the range 6 × 10^–3–4 × 10^–5M, working pH range 1–6 (chlorpromazine); 6 × 10^–3–6 × 10^–5M, pH 1–6 (amitriptyline); 6 × 10^–3–3 × 10^–6M, pH 1–9 (propantheline); and 10^–2–7 × 10^–6M, pH 1–7 (meperidine). The interferences from the alkali and alkaline earth metals were negligible but cationic molecules of similar structure interfered strongly. The electrodes were applied successfully to the assay of active compounds in pharmaceutical preparations. The major advantages of the proposed methods are their simplicity and speed.