Study of Cholesterol—Sitosterol Crystallization Mixtures by DTA

DTA analysis was used to confirm evidence from X‐ray diffraction studies for the existence of 1:1 mixed sitosterol—cholesterol crystals. The curve of melting point against composition has an inflection point at about 1:1 ratio. The DTA peaks for 1:1 mechanical mixtures and for 1:1 mixed crystals are different with respect to symmetry and width. The curve of the heat of enthalpy against the composition of crystals also changes indicating a change in entropy. This can be attributed to the difference between melting mixed crystals (high order) and solid solution (low order). The solubility curve in the sitosterol—cholesterol—alcohol system has also a region of inflection confirming the previous conclusions.