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.