Stable isotope methods for the study of beta-carotene-d8 metabolism in humans utilizing tandem mass spectrometry and high-performance liquid chromatography.
This report presents analytical methods for the isolation and quantification of all-trans-beta-carotene-d8 in human plasma following a 73 mumol oral dose. Retinol-d4 derived from beta-carotene-d8 was also determined in the same plasma. Plasma samples drawn over a 24 day period were analyzed. beta-Carotene and retinol were isolated and purified for analysis using a solid phase extraction protocol with aminopropyl-bonded silica sorbent. Ratios of beta-carotene-d8/beta-carotene were determined using reversed-phase HPLC with spectrophotometric detection, which fully resolved the isotopomers, and by tandem mass spectrometry (MS/MS) with electron ionization. Results obtained from MS/MS and HPLC analysis showed close agreement and demonstrated improved selectivity relative to analysis using a single mass analyzer. Retinol-d4 was converted to its tert-butyldimethylsilyl ether and analyzed by gas chromatography/mass spectrometry using selected ion monitoring. The ability to resolve the beta-carotene isotopomers by HPLC makes it feasible for investigators without mass spectrometers to investigate the dynamics of absorption and metabolism of beta-carotene-d8 in humans.
Department of Nutrition, University of California, Davis 95616.
S R
SR
Dueker
A D
AD
Jones
G M
GM
Smith
A J
AJ
Clifford
D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000097:blood* / Q000302:isolation & purification; D000284:Administration, Oral; D002138:Calibration; D002338:Carotenoids / Q000008:administration & dosage / Q000097:blood* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015203:Reproducibility of Results; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014801:Vitamin A / Q000097:blood / Q000302:isolation & purification; D019207:beta Carotene
D000276:Adjuvants, Immunologic; D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids