Quantitation of Red Blood Cell Folates by Stable Isotope Dilution Gas Chromatography-Mass Spectrometry Utilizing a Folate Internal Standard

✍ Scribed by C.R. Santhoshkumar; J.C. Deutsch; K.L. Hassell; N.M. Kolhouse; J.F. Kolhouse

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 775 KB
• Volume: 225
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1006/abio.1995.1099

✦ Synopsis

We report a new gas chromatography-mass spectrometry (GC-MS) method of measurement of red blood cell folates utilizing a stable isotope-labeled bacterial synthesized folate internal standard. The GC-MS method exploits the fact that the common feature of all folate molecules is a (p)-aminobenzoic acid moiety sandwiched between a pteridine ring and a polyglutamate chain of varying length. In this method, red blood cell folates together with a folate internal standard are specifically purified using bovine folate binding protein and the folates are subsequently chemically cleaved to (\boldsymbol{p})-aminobenzoic acid, pteridines, and glutamic acids. Since all six carbon atoms of the benzene ring in the (p) aminobenzoic acid moiety of the folate internal standard are labeled with (\left[{ }^{13} \mathrm{C}\right]), it is possible to use selected ion monitoring and stable isotope dilution GC-MS to quantitate folates. The method appears to be sensitive, specific, and accurate. The method has been applied to generate a reference range of red blood cell folates based on assay of 25 normal individuals. 1995 Academic Press, Inc.