Quantitation of Choline and Its Metabolites in Tissues and Foods by Liquid Chromatography/Electrospray Ionization-Isotope Dilution Mass Spectrometry

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• 作者：Hasan Koc ; Mei-Heng Mar ; Asoka Ranasinghe ; James A. Swenberg ; and Steven H. Zeisel
• 刊名：Analytical Chemistry
• 出版年：2002
• 出版时间：September 15, 2002
• 年：2002
• 卷：74
• 期：18
• 页码：4734 - 4740
• 全文大小：123K
• 年卷期：v.74,no.18(September 15, 2002)
• ISSN：1520-6882

文摘

Choline is important for normal membrane function,acetylcholine synthesis, lipid transport, and methyl metabolism. The U.S. National Academy of Sciences recentlyset requirements for choline in the human diet. In tissuesand foods, there are multiple choline compounds thatcontribute to choline content. Betaine, a derivative ofcholine, is also important because of its role in donationof methyl groups to homocysteine to form methionine.Radioisotopic, high-pressure liquid chromatography, andgas chromatography/isotope dilution mass spectrometry(GC/IDMS) methods are available for measurement ofcholine. However, these existing methods are cumbersome and time-consuming, and none measures all of thecompounds of interest. In this study, we describe a newmethod for quantitation of choline, betaine, acetylcholine,glycerophosphocholine, cytidine diphosphocholine, phosphocholine, phosphatidylcholine, and sphingomyelin inliver, plasma, various foods, and brain using liquidchromatography/electrospray ionization-isotope dilutionmass spectrometry (LC/ESI-IDMS). Choline compoundswere extracted by and partitioned into organic and aqueous phases using methanol and chloroform and analyzeddirectly by LC/ESI-IDMS without the need for isolationand derivatization of each compound separately as wasrequired by the GC/IDMS method. The new LC/ESI-IDMS method was validated using the existing publishedGC/IDMS method.