title: Use of p-benzoquinone for the spectrophotometric determination of certain sulphonamides.
abstract: A simple spectrophotometric method for the determination of 15 sulphonamides in bulk and in dosage forms is described. The method is based on the interaction of p-benzoquinone with sulphonamides in 0.1 M hydrochloric acid. The resulting chromophore is measured at 500 nm. The effects of different variables on colour development were established. Beer's law was obeyed in a concentration range of 10-50 micrograms ml-1. Results from the analysis of different sulphonamide tablets and ophthalmic solutions marketed locally were in good agreement with that of a reference method. Correlations between A1cm(1%) and certain physical parameters such as pKa values, characteristic volume Vx, and molecular connectivity indices 1X and 1Xv were determined by linear regression equations. A poor correlation was found between A1cm(1%) and bulkiness parameters but a highly significant negative correlation was obtained with apparent pKa values.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Assiut University, Egypt.
authors.forename: A M
authors.initials: AM
authors.lastname: Mohamed
authors.forename: H F
authors.initials: HF
authors.lastname: Askal
authors.forename: G A
authors.initials: GA
authors.lastname: Saleh
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D009883:Ophthalmic Solutions; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet; D013420:Sulfamethoxazole / Q000032:analysis / Q000737:chemistry; D013423:Sulfamoxole / Q000032:analysis / Q000737:chemistry; D013449:Sulfonamides / Q000032:analysis* / Q000737:chemistry; D013607:Tablets; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000032:analysis / Q000737:chemistry
chemical_list: D016227:Benzoquinones; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013607:Tablets; C004532:quinone; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D013423:Sulfamoxole; D013420:Sulfamethoxazole