Conductimetric determination of reproterol HCl and pipazethate HCl and salbutamol sulphate in their pharmaceutical formulations

A simple and sensitive conductimetric method for the determination of salbu tamol sulphate and reproterol and pipazethate hydrochlorides is presented b ased on their ion associates with phosphotungstic and phosphomolybdic acids . The effect of solvent, molar ratio, reagent concentration and temperature were studied, and the solubility products of the formed ion associates wer e calculated. The method was applied to the determination of the drugs in t heir pure state or pharmaceutical preparations with mean recovery values of 99.82-100.54, 99.75-100.12 and 99.95-100.40%, and coefficient of variation 0.28-0.52, 0.16-0.36 and 0.19-0.33 for salbutamol sulphate, reproterol HCl and pipazathate HCl, respectively. (C) 2001 Elsevier Science B.V. All righ ts reserved.