Dissolution enthalpy of sodium sulfacetamide in water: comparison between solution isoperibolic calorimetry and the Van?t Hoff method

TORRES D.R.; SOSNIK A.; CHIAPPETTA D.A.; VARGAS E.F.; MARTINEZ F.

QUíMICA NOVA

Sociedade Brasileira de Química

Año: 2008 vol. 31 p. 1455 - 1459

0100-4042

DISSOLUTION ENTHALPY OF SODIUM SULFACETAMIDE IN WATER: COMPARISON BETWEEN SOLUTION ISOPERIBOLIC CALORIMETRY AND THE VAN?T HOFF METHOD. The dissolution enthalpy (ΔH0soln) of sodium sulfacetamide in water was determined by means of isoperibolic solution calorimetry. It was found that ΔH0soln diminishes as the drug concentration increases. Otherwise, the calorimetric values obtained as a function of the drug concentration were significantly different than those predicted by the van?t Hoff method. It was demonstrated that the later is not a fully reliable method for the determination of ΔH0soln values in the specific case of highly soluble sodium salts. The observed phenomenon could be explained by the presence of strong solute-solute interactions at high salt concentrations, in addition to solute-solvent and solvent-solvent interactions.