Acid-base, spectrophotometric, and colorimetric properties of 1,2-dihydroxyantraquinonone-3-sulfoacid (Alizarin Red S)

Acid-base, spectrophotometric, and colorimetric properties of 1,2-dihydroxyantraquinonone3-sulfoacid (Alizarin Red S, ARS) have been studied in aqueous solutions at pH 3--13. Equations of calibration curves have been obtained for the dependences of absorbance and colorimetric functions (CF) on the ARS concentration. Molar absorption coefficients and CF have been determined. Dissociation constants of ARS have been determined using a spectrophotometric technique in its computational and graphical versions at an ionic strength from 0.1 to 0.5. DOI: 10.1134/S1061934810050072
In the majority of the studies of equilibria in solutions, priority is given to optical techniques, which are based on the dependences of absorbance on the pH of solution [1]. [...]