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Automated measurement of 13 C enrichment in carbon dioxide derived from submicromole quantities of L‐(1‐ 13 C)‐leucine
Author(s) -
Scrimgeour Charles M.,
Smith Kenneth,
Rennie Michael J.
Publication year - 1988
Publication title -
biomedical and environmental mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0887-6134
DOI - 10.1002/bms.1200150704
Subject(s) - mass spectrometry , carbon dioxide , chemistry , contamination , chromatography , ninhydrin , analytical chemistry (journal) , isotopes of carbon , detection limit , leucine , environmental chemistry , biochemistry , organic chemistry , ecology , total organic carbon , biology , amino acid
The 13 C enrichment of the carboxyl carbon of leucine was measured by isotope ratio mass spectrometry after conversion to CO 2 by reaction with ninhydrin in a Vacutainer and cryogenic purification using the Finnigan MAT Breath Gas Analysis System designed for processing 13 C breath test samples. The sources of error which arise with submicromole samples are examined and corrections provided for suboptimal mass spectrometer signals and contamination of the evolved CO 2 with CO 2 from the reaction medium. The main limitations to the accuracy and precision of the method are not instrumental but arise from the contamination with residual CO 2 in the reaction medium, and this sets a lower limit of around 0.25 μmol leucine on the practical sample size. This is an improvement of about five‐fold on the previous manual method of CO 2 isolation.