title: Analysis of isomeric long-chain hydroxy fatty acids by tandem mass spectrometry: application to the diagnosis of long-chain 3-hydroxyacyl CoA dehydrogenase deficiency.
abstract: Acetyl trimethylaminoethyl ester iodide derivatives have been used to selectively analyze isomeric long-chain hydroxy fatty acids by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The binary derivatives of 2-, 3-, 12- and 16-hydroxypalmitic acids afford remarkably different product ion spectra. Further discrimination between isomers is possible by acylating with pivaloyl chloride. 2- and omega-Hydroxy long-chain fatty acids form pivaloyl esters in quantitative yield whereas other secondary alcohols only partially react. Cotton-based filter paper used for blood collection contains substantial amounts of esterified long-chain hydroxy fatty acids. From the product ion spectra of the acetyl trimethylaminoethyl esters the hydroxydocosanoic and -tetracosanoic acids are >90% omega-hydroxy. All remaining saturated and unsaturated hydroxy acids are >90% 2-hydroxy acids. A method for the quantification of free 3-hydroxypalmitic acid in plasma by ESI-MS/MS for the diagnosis of long-chain 3-hydroxyacyl CoA dehydrogenase deficiency (LCHAD) is described. Median plasma concentrations of 0.43 micromol/L (control, n = 22) and 12.2 micromol/L (LCHAD, n = 3) were obtained from 5 microL plasma samples.
authors.affiliation: Department of Chemical Pathology, Women's and Children's Hospital, 72 King William Rd, North Adelaide, South Australia 5006, Australia. david.johnson@adelaide.edu.au
authors.forename: David W
authors.initials: DW
authors.lastname: Johnson
authors.forename: Minh-Uyen
authors.initials: MU
authors.lastname: Trinh
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000172:deficiency*; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005227:Fatty Acids / Q000097:blood* / Q000737:chemistry; D005374:Filtration; D006801:Humans; D007536:Isomerism; D013058:Mass Spectrometry / Q000379:methods; D008661:Metabolism, Inborn Errors / Q000175:diagnosis* / Q000201:enzymology / Q000378:metabolism*; D010169:Palmitic Acids / Q000097:blood / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D005227:Fatty Acids; D010169:Palmitic Acids; C108229:3-hydroxypalmitic acid; D015094:3-Hydroxyacyl CoA Dehydrogenases