COMMON MOLECULAR-SPECIES OF GLUCOSYL CERAMIDES, LACTOSYL CERAMIDES AND SPHINGOMYELINS IN BOVINE-MILK DETERMINED BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

Molecular species of intact glucosyl ceramides, lactosyl ceramides and sphingomyelins were characterized in a sample of polar lipids from bo vine milk (whey). The most common molecular species present in each of the ceramide classes were those with monounsaturated ceramide units o f 34 and 38-42 carbon atoms. Monounsaturated ceramide units with 32, 3 3, 35-37, 44 and 45 carbon atoms were found in low amounts. The satura ted analogues to many of the ceramide units were also found in low amo unts. Normal-phase high performance liquid chromatography on-line with discharge assisted thermospray (''plasmaspray'') mass spectrometry wa s used to separate and characterize the intact ceramide classes. The s pecific long chain base/fatty acid compositions of two ceramide units (34:1 and 40:1) were determined using tandem mass spectrometry.