Comparison of different mass spectrometry techniques in the measurement of L-[ring-13C6]phenylalanine incorporation into mixed muscle proteins

Piotr Zabielski, G. Charles Ford, X. Mai Persson, Abdul Jaleel, Jerry D. Dewey, K. Sreekumaran Nair

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Precise measurement of low enrichment of stable isotope labeled amino-acid tracers in tissue samples is a prerequisite in measuring tissue protein synthesis rates. The challenge of this analysis is augmented when small sample size is a critical factor. Muscle samples from human participants following an 8 h intravenous infusion of L-[ring-13C6]phenylalanine and a bolus dose of L-[ring-13C6]phenylalanine in a mouse were utilized. Liquid chromatography tandem mass spectrometry (LC/MS/MS), gas chromatography (GC) MS/MS and GC/MS were compared to the GC-combustion-isotope ratio MS (GC/C/IRMS), to measure mixed muscle protein enrichment of [ring- 13C6]phenylalanine enrichment. The sample isotope enrichment ranged from 0.0091 to 0.1312 molar percent excess. As compared with GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS showed coefficients of determination of R2 = 0.9962 and R2 = 0.9942, and 0.9217 respectively. However, the precision of measurements (coefficients of variation) for intra-assay are 13.0%, 1.7%, 6.3% and 13.5% and for inter-assay are 9.2%, 3.2%, 10.2% and 25% for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. The muscle sample sizes required to obtain these results were 8 μg, 0.8 μg, 3 μg and 3 μg for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. We conclude that LC/MS/MS is optimally suited for precise measurements of L-[ring-13C6]phenylalanine tracer enrichment in low abundance and in small quantity samples.

Original languageEnglish (US)
Pages (from-to)269-275
Number of pages7
JournalJournal of Mass Spectrometry
Issue number2
StatePublished - Feb 2013


  • GC/MS
  • GC/MS/MS/
  • L-[ring-C]phenylalanine enrichment
  • LC/MS/MS
  • amino-acid tracer
  • mixed muscle proteins
  • tandem mass spectrometry

ASJC Scopus subject areas

  • Spectroscopy


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