Separation of lipoproteins for quantitative analysis of 14C-labeled lipid soluble compounds by accelerator mass spectrometry

Authors: CHUANG, JENNIFER - Nutrilite; CLIFFORD, ANDREW - University Of California, Davis; KIM, SEUNG-HYUN - Konkuk University; FADEL, JAMES - University Of California, Davis; Novotny, Janet; KELLY, PETER - University Of California, Davis; HOLSTEGE, DIRK - University Of California, Davis; WALZEM, ROSEMARY - Texas A&M University

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2024
Publication Date: 2/3/2024
Citation: Chuang, J.C., Clifford, A.J., Kim, S., Fadel, J.G., Novotny, J., Kelly, P.B., Holstege, D.M., Walzem, R.L. 2024. Separation of lipoproteins for quantitative analysis of 14C-labeled lipid soluble compounds by accelerator mass spectrometry. International Journal of Molecular Sciences. 25(3):1856. https://doi.org/10.3390/ijms25031856.
DOI: https://doi.org/10.3390/ijms25031856

Interpretive Summary: Daily requirement for vitamin E has been the subject of debate for decades. One approach to understanding vitamin E requirement is to determine how quickly vitamin E in the body is utilized and eliminated. Tracking vitamin E through the body requires complex methodology, because vitamin E must travel on specialized fat-based packages called lipoproteins and because newly ingested vitamin E must be tagged to discern it from previously ingested vitamin E. A new method for tracing vitamin E through the blood stream has been developed. The new method solves a number of previous problems with methodology for conducting such tracking studies, including improved separation of the different lipoprotein particles that carry vitamin E in the blood stream. Our methodology will allow significant advancements for research on bioavailability and rates of utilization/elimination of fat soluble vitamins like vitamin E. These results will be used by research scientists studying absorption and rates of elimination of fat soluble vitamins.

Technical Abstract: To date, 14C tracer studies using accelerator mass spectrometry (AMS) have not yet resolved lipid-soluble analytes into individual lipoprotein density subclasses. The objective of this work was to develop a reliable method for lipoprotein separation and quantitative recovery for biokinetic modeling purposes. The novel method developed provides the means for use of small volumes (10–200 µL) of frozen plasma as a starting material for continuous isopycnic lipoprotein separation within a carbon- and pH-stable analyte matrix, which, following post-separation fraction clean up, created samples suitable for highly accurate 14C/12C isotope ratio determinations by AMS. Manual aspiration achieved 99.2 ± 0.41% recovery of [5-14CH3]-(2R, 4'R, 8'R)-a-tocopherol contained within 25 µL plasma recovered in triacylglycerol rich lipoproteins (TRL = Chylomicrons + VLDL), LDL, HDL, and infranatant (INF) from each of 10 different sampling times for one male and one female subject, n = 20 total samples. Small sample volumes of previously frozen plasma and high analyte recoveries make this an attractive method for AMS studies using newer, smaller footprint AMS equipment to develop genuine tracer analyses of lipophilic nutrients or compounds in all human age ranges.