This product is a well-defined sulfatide containing a nonadecanoic fatty acid acylated to the amine of the sphingosine making it ideal as an internal standard. Sulfatide is a type of sulfolipid that is found primarily in the central nervous system and is a myelin-specific sphingolipid. A deficiency of sulfatide in white and gray matter has been associated with Alzheimer’s disease and other types of dementia. Apoliprotein E plays an important regulating role in the metabolism of sulfatides.1 The production of anti-sulfatide antibodies in the cerebrospinal fluid, leading to a deficiency in sulfatides, may be a cause of degeneration of the myelin sheath, leading to multiple sclerosis and other demyelinating diseases.2 Metachromatic leukodystrophy is an inherited disorder characterized by a deficiency of the lysosomal enzyme arylsulfatase A and the subsequent accumulation of sulfatide in neural and visceral tissues.3 Sulfatide also regulates the differentiation of oligodendroblasts. Central nervous system (CNS) myelin is strongly inhibitory to growing axons and sulfatides present in the myelin of the CNS have been identified as major myelin-associated axon growth inhibitors.4 A low level of serum sulfatides has been linked with an increased risk of cardiovascular disease in some situations. Sulfatides in the myelin, especially cistetracosenoyl- sulfatides, stimulate a distinct population of CD1d-restricted natural killer T cells giving these sulfatides important implications for the design of therapeutics that target T cells reactive for myelin glycolipids in autoimmune diseases of the central nervous system.5