New methods for determining the enantiomeric purity of erythro-sphingosine

The enantiomeric purity of erythro-sphingosine samples can be determined si mply, reliably, and accurately from H-1 or F-19 nuclear magnetic resonance spectra of the alpha-methoxy-alpha-(trifluoromethyl)phenylacetate (MTPA) de rivative. As little as 0.1% of the minor enantiomer could be observed in a l-mg sample, and detection limits of 1% and 5% were estimated for samples o f 100 mu g and 10 mu g. The two threo-sphingosine enantiomers and four dihy drosphingosine stereoisomers were also differentiated by this technique, wh ich served as an effective method for assessing the purity of sphingosine a nd dihydrosphingosine samples. Enantiomeric and diastereomeric purities cou ld also be determined by normal-phase high performance liquid chromatograph ic analysis of the MTPA derivatives.