The enantiomeric purity control of ephedrine-HCl, norephedrine-HCl, ma
ndelic acid and levamisole-HCl is investigated by means of DSC and CD.
The precision of thermal analysis increases with the difference of me
lting points between enantiomer and eutectic. The interpretation of me
lting enthalpy is more trustworthy than the onset temperature of melti
ng. The thermogravimetric noticeable decomposition of levamisole prohi
bits the DSC purity control, because the onset temperature of degradat
ion is below he melting temperature, The CD of ephedrine and levamisto
le is in the same size, therefore the purity of these compounds is det
erminable with the same precision (s(rel) +/- 3%). The CD investigatio
n in solution is preferable to the thermic solid matter analysis.