Journal of the American Society for Mass Spectrometry

, Volume 7, Issue 6, pp 605–610

Direct analysis of carbon isotope variability in albumins by liquid flow-injection isotope ratio mass spectrometry

  • Richard J. Caimi
  • J. Thomas Brenna
Short Communication

DOI: 10.1016/1044-0305(96)00010-4

Cite this article as:
Caimi, R.J. & Brenna, J.T. J Am Soc Mass Spectrom (1996) 7: 605. doi:10.1016/1044-0305(96)00010-4


We demonstrate the high precision C isotopic analysis of a series of purified albumins by liquid chromatography-combustion isotope ratio mass spectrometry (IRMS) by using direct aqueous liquid injection. Albumins from 18 species and albumens from chicken and turkey egg were obtained from a commercial source and shown to be of > 98% purity by capillary zone electrophoresis and high-performance liquid chromatography. One microliter of an aqueous protein solution with a total of < 40-pmol protein (2. 5 µg), which contained about 150-nmol C, was injected directly into a flowing stream of high-performance liquid chromatography grade water. The solution passed through a pneumatic nebulizer, was sprayed onto a moving wire, passed through a drying oven, and was combusted in a furnace. After the water of combustion was removed, the resulting CO2 gas was directed to a high precision IRMS instrument operated in continuous flow mode. The average precision across the 20 samples analyzed was SD(δ13C)=0.45%., and the average accuracy was δ13C < 0.4%. compared to aliquots analyzed by conventional preparation by using combustion tubes and dual inlet analysis. The observed isotope ratio range was about −22.5%. < δ13CPDB < −16%. as expected for modern materials from a natural source. These results demonstrate rapid, high precision, and accurate C isotopic analysis of untreated macromolecules in an aqueous stream by liquid source IRMS.

Copyright information

© American Society for Mass Spectrometry 1996

Authors and Affiliations

  • Richard J. Caimi
    • 1
  • J. Thomas Brenna
    • 1
  1. 1.Division of Nutritional SciencesCornell UniversityIthacaUSA
  2. 2.Cornell UniversityIthaca