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Croatica Chemica Acta, Vol. 82 No. 4, 2009.

Original scientific paper

Spectrophotometric Determination of the Dissociation Constants of Fluorescein in Micellar Media

Ali Niazi ; Department of Chemistry, Faculty of Sciences, Islamic Azad University, Arak Branch, Arak, Iran; Yong Researches Club, Islamic Azad University, Arak Branch, Arak, Iran
Ateesa Yazdanipour ; Department of Chemistry, Faculty of Sciences, Islamic Azad University, Arak Branch, Arak, Iran
Jahanbakhsh Ghasemi ; Department of Chemistry, Faculty of Sciences, K. N. Toosi University of Technology, Tehran, Iran
Mikael Kubista ; Institute of Biotechnology AS CR, v.v.i, Videnska 1083, 142 20 Prague, Czech
Azemat Sheyda ; Department of Chemistry, Faculty of Sciences, Islamic Azad University, Arak Branch, Arak, Iran
Mahtab Alikhah ; Department of Chemistry, Faculty of Sciences, Islamic Azad University, Arak Branch, Arak, Iran

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Abstract

The investigation of the dissociation equilibrium of fluorescein in aqueous micellar solution was determined spectrophotometrically at 25 °C and at ionic strength of 0.1 mol dm−3. For this purpose, the effect of nonionic (TX100), cationic (CTAB) and anionic (SDS) surfactants on the absorption spectra of fluorescein at different pH values were studied. To evaluate the pH-absorbance data, a resolution based on the combination of soft- and hard-modeling is applied. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data to an established factor analysis model. DATAN program was applied for determination of acidity constants. Results show that the pKa values of fluorescein are influenced as the percentages of an anionic and a cationic surfactant such as SDS and CTAB, respectively, are added to the solution of this reagent. Also, neutral surfactant such as TX100 only affects pKa1. Effects of surfactant on acidity constants and pure spectrum of each component are also discussed.

Keywords

fluorescein; acidity constants; TX100; SDS; CTAB; DATAN; spectrophotometric

Hrčak ID:

45615

URI

https://hrcak.srce.hr/45615

Publication date:

20.12.2009.

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