Methods for methanolysis of sphingolipids and direct determination of long‐chain bases by gas chromatography

Abstract A new, simple procedure is described for the direct gas chromatographic determination of sphingolipid bases as their trimethylsilyl derivatives. This method is used to study the nature of the mixture of bases produced by acidic methanolysis of ceramides, sphingomyelins, free sphingolipid bases, and N ‐acetyl derivatives of the latter. Cleavage of sphingolipids with anhydrous methanolic hydrogen chloride results in the production of considerable quantities of secondary products from sphingosine, such as the O ‐methyl ethers, which are not formed during methanolysis of free sphingosine. A modified reagent for methanolysis, containing methanol, water and hydrochloric acid, reduces the yield of these by‐products to low levels. Preliminary purification of the sphingolipid bases, before gas chromatography, is achieved by chromatographic procedures. Evidence is presented for the occurrence of C 16 ‐sphingosine in sphingomyelin from human blood plasma.