The
hydration/dehydration behavior of aspartame revisited
C. Guguta, H. Meekes and R. de Gelder
J. of Pharmaceutical and Biomedical
Analysis 46 (2008) 617-624
Abstract:
Aspartame, l-aspartyl-l-phenylalanine methyl ester, has two hydrates
(IA and IB), a hemi-hydrate (IIA) and an anhydrate (IIB). The
hydration/dehydration behavior of aspartame was investigated using
hot-humidity stage X-ray powder diffraction (XRPD) and molecular
mechanics modeling in combination with differential scanning
calorimetry (DSC) and thermogravimetric analysis (TGA). The results of
this study are compared to earlier studies on aspartame as described in
literature. It is shown that earlier transition studies were hampered
by incomplete conversions and wrong assignment of the forms. The
combination of the techniques applied in this study now shows
consistent results for aspartame and yields a clear conversion scheme
for the hydration/dehydration behavior of the four forms.