SPECTROPHOTOMETRIC DETERMINATION OF SOME PHARMACEUTICAL THIOLS USING 2,6-DICHLOROQUINONE-4-CHLORIMIDE

El-Kommos, M. E.; Mohamed, H. A.; Abdelmageed, O. H.; Mohamed, N. A.

doi:10.21608/bfsa.1993.70042

SPECTROPHOTOMETRIC DETERMINATION OF SOME PHARMACEUTICAL THIOLS USING 2,6-DICHLOROQUINONE-4-CHLORIMIDE

Document Type : Original Article

Authors

Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt

10.21608/bfsa.1993.70042

Abstract

The reaction of thiols with 2,6-dichloroquinone-4-chlorimide (DQC) at pH 7-8 was applied to the quantitative determination of 9 thiol compounds related to different classes (aliphatic, aromatic and heterocyclic). The aliphatic thiols yielded a yellow color (l_max 435 nm) aromatic thiols yielded an orange color (l_max 498-503 nm), sulphathiourea, 2-thiobarbituric acid and thiacetazone yielded violet colors (l_max 540-550 nm). Job's plots indicate a 1:1 ratio of thiol to reagent. Beer-lambert's law is adhered to over the following ranges 2-4 mg ml^-1 (for 2-thiobarbituric acid), 3-6 mg ml^-1 (for thiosalicylic acid), 4-18mg ml^-1 (for thiomersal), 2-14 mg ml^-1 (for thiacetazone) 10-70 mg ml^-1 (for captopril), 5-25mg ml^-1 (for dimercaprol), 10-40 mg ml^-1 (for thioglycerol) and 5-30 mg ml^-1 (for tiopronin). Common tablet excipient as well as additives in parenteral solutions were found not to interfere. The results of analysis of pure drugs and their dosage forms by the proposed method are ingood agreement with those obtained by official and reported methods.