EQUILIBRIUM CONSTANTS DETERMINATION OF ASCORBIC ACID IN AQUEOUS MEDIUM BY POLARIMETRY

In this work, the acid constants of ascorbic acid (AA) by polarimetry, with a base titration of the acid, aredetermined. The results obtained by this technique were processed by adjusting the rotation angles measuredas a function of the pH, using for the fitting the Biot and additivity laws for this property. Non-linear and linearregression models were applied. The most reliable values obtained were pKa1 = 4.149 0.022 and pKa2 =11.927 0.062, achieved by non-linear regression of the data acquired to ? = 578 nm, with standard deviationsfor the fit equal to 0.046? and 0.075?, respectively. These values are comparable with those reported usingother techniques.