Continuous flow isotope ratio mass spectrometry for the measurement of nanomole amounts of (13)CO(2) by a reverse isotope dilution method.
A simple method for the determination of nanomole amounts of (13)CO(2) generated from an in vitro reaction is reported. The incubation medium contains a known amount of unlabeled sodium bicarbonate and the gaseous (13)CO(2) enriches the atmosphere upon which a measurement of the isotopic enrichment ((13)CO(2)/(12)CO(2)) is made corresponding to a reverse isotope dilution. The quantification of the (13)CO(2) was performed by gas chromatography/isotope ratio mass spectrometry. This assay was validated in terms of linearity, accuracy and precision using three different substrates which produce (13)CO(2) either by enzymatic reaction [(13)C]urea, sodium [(13)C]formate) or by chemical reaction (sodium [(13)C]bicarbonate). Four calibration curves were tested for each (13)C-labeled substrate, allowing the quantification of (13)CO(2) from 25 pmol to 150 nmol. The dynamics of the assay were obtained as a function of the quantity of unlabeled sodium bicarbonate added to each sample.
Guitton
J
J
Fédération de Biochimie, Laboratoire de Biochimie C, Hôpital E. Herriot, 69437 Lyon Cedex 03, France. jerome.guitton@laennec.univ-lyon1.fr
Grand
F
F
Magat
L
L
Désage
M
M
Francina
A
A
D000465:Algorithms; D002138:Calibration; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes; D005561:Formates / Q000737:chemistry; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D011865:Radioisotope Dilution Technique; D015203:Reproducibility of Results; D017693:Sodium Bicarbonate / Q000737:chemistry; D014508:Urea / Q000737:chemistry
D002247:Carbon Isotopes; D005561:Formates; D007202:Indicators and Reagents; C030544:formic acid; D002245:Carbon Dioxide; D017693:Sodium Bicarbonate; D014508:Urea