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Analysis of isomeric long‐chain hydroxy fatty acids by tandem mass spectrometry: application to the diagnosis of long‐chain 3‐hydroxyacyl CoA dehydrogenase deficiency
Author(s) -
Johnson David W.,
Trinh MinhUyen
Publication year - 2002
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.889
Subject(s) - chemistry , electrospray ionization , tandem mass spectrometry , chromatography , fatty acid , iodide , mass spectrometry , organic chemistry
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 ω‐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% ω‐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 μmol/L (control, n = 22) and 12.2 μmol/L (LCHAD, n = 3) were obtained from 5 μL plasma samples. Copyright © 2002 John Wiley & Sons, Ltd.