The Use of GC-C-IRMS for the Analysis of Stable Isotope Enrichment in Nitrogenous Compounds

The relative natural abundance of the main heavy stable isotopes in bioelements (²H, ¹³C, ¹⁵N, ¹⁸O) is generally considered as fixed. However, it varies in subtle limits (± 10^-4 - 10^-2 atom %; AP), due to various isotope fractionation processes in nature. The specialized instrument dedicated to measure such small differences precisely is a gas isotope ratio mass spectrometer (GIRMS), which requires the introduction of the sample as pure gas.