- 2, 3-Dichloro-5, 6-Dicyano-1,4-Benzoquinone as Redox Titrant

Abstract

An oxidimetric titrant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in glacial acetic acid is used for the semimicro-determination of some sulphur containing drugs such as: N acetylcysteine, captopril, ethamsylate, carbocisteine, and thioctic acid in pure forms as well as in some pharmaceutical dosage forms. The equivalence point is detected potentiometrically using a platinum/calomel electrode system or visually by certain phenothiazine derivatives. Satisfactory percentage recoveries are obtained; (100.61±0.67) for N-acetylcysteine , (99.6±0.7) for captopril ,(100.1±0.74) for ethamsylate, (99.27±1.35) for carbocisteine and (99.7±1.85) for thioctic acid with a minimum quantitative limit about 1 mg. These results are favourably compared statistically with the reference methods. The proposed procedure is characterized by simplicity, accuracy and precision.