POTENTIOMETRIC AND SPECTROPHOTOMETRIC DETERMINATION OF THE DISSOCIATION-CONSTANTS OF CEFETAMET

The dissociation constants of cefetamet-Na have been determined using potentiometric titrations and spectrophotometry. The investigations we re carried on in water solutions at constant temperature and ionic str ength, and at different H-0 and pH values. Potentiometric investigatio ns were performed at three different temperatures and ionic strengths. The concentration dissociation constants and the corresponding thermo dynamic dissociation constants were calculated by a computer program. The mixed dissociation constants (pK') of cefetamet-Na have been deter mined spectrephotometrically in the Ho range from -5.80 to 0.00 and at pH values from 0.00 to 12.70 and are in good agreement with values ac hieved by graphical methods as well as with those obtained by potentio metric methods. Based on the determined values, the thermodynamic para meters (Delta G, Delta H, Delta S) were calculated at I = 0.1 M.