Direct determination of triamterene by potentiometry using a coated wire selective electrode

A coated wire triamterene-selective electrode based on the incorporation of a triamterene-tetraphenylborate ion-pair in a poly(vinylchloride) coating membrane was constructed. The influence of membrane composition, temperature, pH of the test solution, and foreign ions on the electrode performance were investigated. The electrode showed a Nernstian response over a triamterene concentration range from 1.0 x 10(-6) to 3.5 x 10(-2) M, at 25 degreesC, and was found to be very selective, precise, and usable within the pH range 4.5-7.5. The standard electrode potentials, Edegrees, were determined at 15, 20, 25, 30, 35, 40 and 45 degreesC and used to calculate the isothermal temperature coefficient (dEdegrees/dt) of the electrode. Temperatures higher than 45 degreesC seriously affected the electrode performance. The electrode was successfully applied to the potentiometric determination of triamterene hydrochloride both in pure solutions and in pharmaceutical preparations. (C) 2003 Elsevier B.V. All rights reserved.