title: Spectrophotometric determination of acidity constant of some indicators in various micellar media solutions by rank annihilation factor analysis.
abstract: Rank annihilation factor analysis (RAFA) was used to the spectrophotometric studies of the acidity constant of methyl orange, methyl red and methyl violet in water and different micellar solutions at 25 degrees C and an ionic strength of 0.1M. When the acidity constants (surfactant concentration dependent acidity constant) acts as an optimizing object, and simply combined with the pure spectrum of acidic and basic forms, the rank of original data matrix can be reduced. The residual standard deviation (R.S.D.) of the residual matrix after bi-linearization of the background matrix is regarded as the evaluation function. Results show that the acidity constant of these indicators are influenced as the percentages of neutral, cationic and anionic surfactant such as Triton X-100 (poly(oxyethylene)(9.5)p-(1,1,3,3-tetramethyl), sodiumdodecylsulfate (SDS) and cethyltrimethylammonium (CTAB), respectively, added to the solution of these reagents. Also, RAFA is an efficient chemometrics algorithm for completely analysis of acid-base equilibrium systems by spectrophotometric method. Effects of surfactant on acidity constant and absorption spectra are also discussed.
authors.affiliation: Chemistry Department, Faculty of Sciences, Azad University of Arak, Arak, Iran. ali.niazi@gmail.com
authors.forename: Ali
authors.initials: A
authors.lastname: Niazi
authors.forename: Javad
authors.initials: J
authors.lastname: Zolgharnein
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Davoodabadi
mesh_terms: D001391:Azo Compounds / Q000032:analysis; D005840:Gentian Violet / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000032:analysis*; D008823:Micelles; D009994:Osmolar Concentration; D012996:Solutions; D013053:Spectrophotometry / Q000379:methods*; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D007202:Indicators and Reagents; D008823:Micelles; D012996:Solutions; D013501:Surface-Active Agents; D014867:Water; C008492:methyl red; C100258:methyl orange; D005840:Gentian Violet