New methods for determining the enantiomeric purity of erythro -sphingosine

The enantiomeric purity of erythro -sphingosine samples can be determined simply, reliably, and accurately from 1H or 19F nuclear magnetic resonance spectra of the alpha-methoxy-alpha-(trifluoromethyl)phenylacetate (MTPA) derivative. As little as 0.1% of the minor enantiomer could be observed in a 1-mg sample, and detection limits of 1% and 5% were estimated for samples of 100 microg and 10 microg. The two threo -sphingosine enantiomers and four dihydrosphingosine stereoisomers were also differentiated by this technique, which served as an effective method for assessing the purity of sphingosine and dihydrosphingosine samples. Enantiomeric and diastereomeric purities could also be determined by normal-phase high performance liquid chromatographic analysis of the MTPA derivatives.