colorimetric method for analysis of phenolphthalein

ABSTRACT

A colorimetric procedure for the determination of phenolphthalein based upon its condensation with 4-aminophenazone in presence of an alkaline oxidizing agent and measuring the absorbance at 460 nm, is proposed. The procedure determines 0.08-0.6 mg/25 ml with mean recovery of 99.54 +/- 0.64%. The method is compared by the British Pharmacopoeia [1980] method and is applied to the determination of phenolphthalein in pharmaceutical preparations. The proposed procedure is not interferred with by other compound usually formulated with phenolphthalein