title: Determination of aromatic hydrotropic drugs in pharmaceutical preparations by the surfactant-binding degree method.
abstract: An aggregation parameter-based analytical approach, the surfactant-dye binding degree (SDBD) method, was used, for the first time, to determine aromatic hydrotropic compounds. The anionic dye Coomassie Brilliant Blue G (CBBG) was used as inductor of didodecyldimethylammonium bromide (DDABr) aggregates, whose formation was monitored from changes in the spectral features of the dye. Interactions between hydrotrope and DDABr molecules resulted in a decrease of the degree of binding of the cationic surfactant to CBBG, which was proportional to the concentration of hydrotrope in the aqueous solution. The CBBG-DDABr-hydrotrope chemical system was found to fit to the mathematical expression previously derived for the determination of amphiphilic compounds. The hydrotrope-surfactant bond strength determined the sensitivity achieved for the determination of hydrotropic compounds, which was highly dependent on the molecular structure of the analyte. The high precision (the relative standard deviation for 7 mg l(-1) of salicylic acid was 0.8%), rapidity (measurements were performed in a few minutes) and low cost (in both instrumentation and reactants) of the proposed method, made it especially suitable for quality control. The practical analytical applicability of the SDBD method for the control of hydrotropic drugs in pharmaceutical preparations was demonstrated by quantifying salicylic acid and acetyl salicylic acid in liquid (solutions) and solid (tablets, granulates, unguents, gels and creams) samples, which were directly analyzed after dissolution of the samples.
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Córdoba, Edificio Anexo Marie Curie, Campus de Rabanales, 14071-Córdoba, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Pedraza
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Sicilia
authors.forename: Soledad
authors.initials: S
authors.lastname: Rubio
authors.forename: Dolores
authors.initials: D
authors.lastname: Pérez-Bendito
mesh_terms: D002626:Chemistry, Pharmaceutical; D004396:Coloring Agents; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012394:Rosaniline Dyes; D012995:Solubility; D012996:Solutions; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D004364:Pharmaceutical Preparations; D012394:Rosaniline Dyes; D012996:Solutions; D013501:Surface-Active Agents; C004692:coomassie Brilliant Blue