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United States Department of Agriculture

Agricultural Research Service

Title: A Stable Isotope Lc-Ms Procedure to Study the Metabolism of 2h8-Beta Carotene in Huamns (Experimental Biology '99)

item Pawlosky, Robert
item Novotny, Janet
item Flanagan, Vincent

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 1999
Publication Date: April 15, 1999
Citation: Pawlosky, R.J., Novotny Dura, J., Flanagan, V.P. 1999. A stable isotope lc-ms procedure to study the metabolism of 2h8-beta-carotene in humans (experimental biology '99). Meeting Abstract.

Technical Abstract: All trans beta-carotene (BC), a nutrient present in green leafy vegetables and in fruits, is a precursor to all- trans retinol (vitamin-A). The absorption of BC and its synthesis into vitamin-A is influenced by dietary factors. In the liver, BC is converted to retinol. Other precursors of vitamin-A (retinyl esters) are madein the intestine. In addition, some of the all- trans compound may be isomerized to cis isomers. The absorption of all trans BC and its conversion to other compounds was studied using a newly developed procedure based on liquid chromatography- mass spectrometry (LC-MS). The analysis of (2H8)-labeled BC (and endogenous unlabeled compounds) and 2H4-retinol species from plasma will be described here. 20 microliters of the hexane- extracted plasma (30ul of plasma) were resolved on a C-18 column by HPLC using an organic solvent mobile phase. The analytes were detected using an in-line UV diode array detector (450 or 325 nm), the solvent effluent was then removed by passing it through a particle beam transfer line interfaced to a quadrupole mass spectrometer. The eluites were ionized using methane gas and analyzed in the negative ion mode. An isotopically labeled internal standard (13C30-BC) was used to quantify the carotenoid species and 2H8-retinol was used to quantify vitamin-A.

Last Modified: 4/22/2015
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