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Rapid sample throughput for biomedical stable isotope tracer studies
Author(s) -
Preston T.,
McMillan D. C.
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.1200160142
Subject(s) - isotope , chemistry , isotope ratio mass spectrometry , stable isotope ratio , tracer , mass spectrometry , isotope analysis , chromatography , sample preparation , isotopic labeling , substrate (aquarium) , metabolomics , analytical chemistry (journal) , organic chemistry , ecology , physics , oceanography , quantum mechanics , nuclear physics , biology , geology
Typical 13 C or 15 N tracer studies generate large numbers of samples. Instrumentation capable of rapid automated analysis is therefore of importance as a practical alternative to conventional isotope methodology. Although biomedical sample nature is diverse, experimenters often require analysis of substrates and products of particular biochemical pathways. Clearly, reaction products can contain considerably less isotope tracer than precurosors. Analytical techniques thus need to accommodate samples of widely varying nature, size and isotope enrichment. In the clinical field, where stable isotopes are increasingly used to study protein, carbohydrate and fat metabolism, analysis of the isotope ratio of a substrate infused into the plasma and a product of its metabolism is often required. Conventional analytical approaches demand access to two mass spectrometers: isotope ratio mass spectrometry (IRMS) for isotope analysis of the relatively large concentrations of low‐enrichment metabolic product, and gas chromatography/mass spectrometry (GC/MS) for analysis of the infused substrate often present at high enrichment but low concentration. The recent development of continuous‐flow IRMS (CF‐IRMS) combined with preparative chromatography offers a practical alternative to the conventional approaches that is rapid and automatic. In addition to providing a considerably less complex and costly alternative to conventional instrumentation, a single CF‐IRMS instrument can also analyse small quantities of low‐enrichment metabolites with superior performance than either of the alternative approaches. CF‐IRMS is illustrated using results from constant‐infusion studies in human protein and fat metabolism which require measurement of the isotope enrichment in submicromolar quantities of plasma substrates together with analysis of larger quantities of their oxidation products, urinary nitrogen and breath CO 2 .