Determination of potassium in pharmaceutical formulations by means of 18-crown-6: extraction studies

A colorimetric method has been developed for the determination of potassium in pharmaceutical formulations. The method is based on the formation of a complex of potassium with 18-crown-6, followed by conversion to an ion-pair with picrate anion; the ion-pair is extracted with either methylene chloride or toluene-methylene chloride (80:20, v/v) and determined colorimetrically.