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Analysis of (1‐ 13 C)leucine and ( 13 C)KIC in plasma by capillary gas chromatography/mass spectrometry in protein turnover studies
Author(s) -
Ford G. C.,
Cheng K. N.,
Halliday D.
Publication year - 1985
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200120814
Subject(s) - chemistry , leucine , chromatography , metabolite , mass spectrometry , gas chromatography–mass spectrometry , gas chromatography , selected ion monitoring , chemical ionization , amino acid , ion , ionization , biochemistry , organic chemistry
The methods used for the determination of the concentration and isotope enrichment of (1‐ 13 C)leucine and its metabolite ( 13 C)α‐ketoisocaproic acid (KIC) in plasma for the study of whole‐body protein turnover are described. Leucine was analysed as its N ‐heptafluorobutyryl isobutyl ester and KIC as its quinoxalinol‐TMS derivative, both by chemical ionization selected ion monitoring gas chromatography/mass spectrometry (GC/MS). The sensitivity of the leucine assay was improved 30 times by monitoring the negative ions under the conditions described. The coefficient of variation for enrichment and concentration measurements were 0.5% and 2%, respectively, with a minimum detectable enrichment of 0.1at% excess for both assays.