Determination of leucine flux in vivo by gas chromatography-mass spectrometry utilizing stable isotopes for trace and internal standard

J Chromatogr. 1980 Oct 10;183(4):403-9. doi: 10.1016/s0378-4347(00)81582-0.


A simple and reliable method is described for the determination of leucine flux in vivo using two stable isotopes of leucine and gas chromatography-mass spectrometry (GC-MS). [6,6,6-2H3]Leucine is administered as a primed-dose constant infusion in vivo and DL-[2H7]-leucine is added to plasma as an internal standard. Plasma leucine concentration and moles per cent enrichment of [2H3]leucine can be determined simultaneously by GC-MS and selected ion monitoring. Leucine flux calculated from the [6,6,6-2H3]leucine data was nearly identical to that obtained with L-[U-14C]leucine in dogs. This method is readily applicable to the study of leucine metabolism in humans of all ages and laboratory animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Deuterium
  • Dogs
  • Gas Chromatography-Mass Spectrometry / methods*
  • Infusions, Parenteral
  • Leucine / administration & dosage
  • Leucine / blood*


  • Deuterium
  • Leucine