Very-Long-Chain Fatty Acids Quantification by Gas-Chromatography Mass Spectrometry.

Abnormal accumulation of very-long-chain fatty acids (VLCFAs), defined as molecules with greater than 22 carbons, and branched-chain fatty acids, pristanic and phytanic acids, is characteristic of inborn errors of peroxisomal biogenesis or function. X-linked adrenoleukodystrophy, Zellweger spectrum disorders, rhizomelic chondrodysplasia punctata, and Refsum syndrome can be diagnosed biochemically by quantitation of these metabolites in plasma. Ratios of C24/C22 and C26/C22 can help improve detection of X-linked adrenoleukodystrophy. Analysis using gas-chromatography mass spectrometry (GC/MS) after acid/base hydrolysis, organic solvent extraction, and derivatization is an established method for clinical diagnostics. This chapter describes detailed steps to process plasma samples for GC/MS analysis.