Determination of Protonation Constants of Viral Inhibitor, Aurintricarboxylic Acid in SDS and CTAB Micellar Media: A Potentiometric Study

K. Bhargavi1,, P. Shyamala1,*, and G. Nageswara Rao2,

1Department of Physical and Nuclear Chemistry & Chemical Oceanography, School of Chemistry, Andhra University, Visakhapatnam-530003, India

2Department of Inorganic and Analytical Chemistry, School of Chemistry, Andhra University, Visakhapatnam-530003, India

*Corresponding author: E-mail:


Protonation constants of a viral inhibitor, aurintricarboxylic acid were determined using potentiometric method of data acquisition followed by chemometric modelling methods of analysis in the presence of two different kinds of micellar media, CTAB, a cationic micelle and SDS, an anionic micelle. MINIQUAD75 program was used for the determination of the plausible species and their corresponding formation constants at 303 ± 0.1 K and 0.01 M ionic strength. Five formation constants were identified corresponding to five ionizable hydrogens. Species concentration distribution diagrams were generated using Origin software. Best-fit chemical models were selected on the basis of statistical parameters like standard deviation (SD), U (sum of the squares of the residuals in mass balance equations) and chi-square test. It was found that the formation constants are lower in CTAB micellar medium while there is no significant change in the presence of SDS compared to aqueous medium.


Aurintricarboxylic Acid, Sodium dodecyl sulfate, Cetyltrimethylammonium bromide, Protonation constant.

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