Simplified derivatization for determining sphingolipid fatty acyl composition by gas chromatography-mass spectrometry

A simple procedure for simultaneously derivatizing non-hydroxy and hydroxy fatty acids prior to GC analysis [I. Ciucanu and F. Kerek, J. Chromatogr., 284 (1984) 179] has been evaluated for its usefulness in determining sphingolipid acyl composition. The method uses methyl iodide in polar aprotic solvents to generate methyl esters of carboxyl groups and methyl ethers of hydroxyl groups. Methylation efficiency is examined as a function of hydroxyl group presence and location in free fatty acids as well as a function of 2-hydroxy fatty acid chain length. Conditions are also reported for efficient saponification and derivatization of sphingolipid fatty acyl chains as is illustrated using bovine brain galactosylceramide.