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Analysis of Vitamin A Stable Isotope Tracers using LC-MS/MS

Lookup NU author(s): Professor Georg LietzORCiD, Dan AstleyORCiD, Alice Goddard, Dr Anthony OxleyORCiD

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).

Abstract

The retinol isotope dilution (RID) method estimates the total body stores (TBS) of vitamin A in humans through stable isotope dilution with the body's vitamin A pool. For this, it is critical to accurately and efficiently determine the plasma isotopic ratio of labeled to non-labeled retinol through mass spectrometry. To avoid extensive and time-consuming extraction and/or purification procedures, such as preparative HPLC and derivatization, LC-MS/MS is employed to conduct fast, sensitive, and simultaneous analysis of labeled and non-labeled retinoids. The method utilizes two levels of detection: (i) an initial mass/charge (m/z) separation of parent (precursor) ions, followed by (ii) detection of fragmented daughter (product) ions. This results in high sensitivity, with retinol detection limits as low as 6 fmol on-column. Despite the advantages of tandem mass spectrometry, a liquid chromatographic separation is required to separate retinol from retinyl esters since the terminal functional groups are lost during ionization, resulting in similar parent (m/z of 269) and daughter ion fragmentation patterns. The article describes the isolation of endogenous and labeled (13C or 2H) retinol from plasma by solvent extraction, followed by quantification by LC-MS/MS under atmospheric pressure chemical ionization (APCI) in positive ion mode.

Publication metadata

Author(s): Lietz G, Astley D, Goddard A, Oxley A

Publication type: Article

Publication status: Published

Journal: Journal of Visualized Experiments

Year: 2025

Online publication date: 30/12/2025

Acceptance date: 01/12/2025

Date deposited: 21/01/2026

ISSN (electronic): 1940-087X

Publisher: Journal of Visualized Experiments

URL: https://doi.org/10.3791/69558

DOI: 10.3791/69558

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Funding

Funder referenceFunder name
Bill & Melinda Gates Foundation (Project Number: OPP1115464)
International Atomic Energy Agency (IAEA) in Vienna (Project Number E4.30.30)

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