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Isotope dilution studies: Determination of carbon‐13, nitrogen‐15 and deuterium‐enriched compounds using capillary gas chromatography—chemical reaction interface/mass spectrometry
Author(s) -
Chace Donald H.,
Abramson Fred P.
Publication year - 1990
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.1200190305
Subject(s) - deuterium , chemistry , mass spectrometry , isotope dilution , chromatography , gas chromatography , gas chromatography–mass spectrometry , isotope ratio mass spectrometry , analytical chemistry (journal) , capillary action , materials science , nuclear physics , composite material , physics
In addition to the ability of a capillary gas chromatographic‐chemical reaction interface/mass spectrometric technique (CRIMS) to detect the presence of 13 C, 15 N and 2 H (D) it can also quantify the level of the enriched substance. The microwave‐powered chemical reaction interface converts materials from their original forms into small molecules whose mass spectra serve to identify and quantify the nuclides which make up each analyte. The presence of enrichment of each element is followed by monitoring the isotopic variants of CO 2 , NO or H 2 which are produced in the chemical reaction interface. Chromatograms showing only enriched 13 C and 15 N are produced by subtracting the abundance of naturally occurring isotopes from the observed M + 1 signal. A selective chromatogram of 2 H (D) is obtained by measuring HD at m / z 3.0219 with a resolution of 2000. Enrichment of 13 C and 15 N is quantified by measuring the ratio of excess 13 CO 2 to total 12 CO 2 or excess 15 NO to total 14 NO. To evaluate linearity and detection limits, we have used phenytoin as an example of an unlabeled substance and added various labeled phenytoin analogs. Atom enrichments of 0.3% were detectable for (2,4,5− 13 C 3 ) phenytoin and 0.06% for (1,3− 15 N 2 )labeled phenytoin, each in the presence of 500 ng of unlabeled phenytoin, respectively. For deuterium, enrichment could not be directly determined. However, 1 ng of (ring D 10 ) phenytoin was determined in the presence of 500 ng of unlabeled diethylated phenytoin. We have found CRIMS capable of quantifying 13 C‐, 15 N‐ and D‐enriched substances.