High precision QCL based direct detection of stable isotopes and tracers in bio-geoscience

To study the geochemical cycles of important greenhouse gases, it is helpful to go beyond measuring their concentrations. Measurements of isotopic ratios can help identify emission sources and study biological and chemical processes. This can include laboratory incubation experiments in soil, agricultural and grass lands, wastewater, and other microbial active aqueous solutions.

The abundances of the ¹⁵N and ¹⁸O isotopes can be compared to the main isotope ¹⁴N¹⁴N¹⁶O, revealing the distinct isotopic signatures. As a linear molecule with two nitrogen atoms, N₂O has two structural isomers of identical mass, which cannot be distinguished by mass spectroscopy. Therefore, a geometry sensitive laser spectroscopy-based approach is required.

The new MGAⁱ-N₂O from MIRO Analytical simplifies the monitoring of N₂O isotopic composition by enabling simultaneous online measurements of up to 5 major isotopologues of N₂O at high measurement rates, while providing excellent stability and precision at a fraction of the cost of isotope mass spectrometers. 

In our presentation we will demonstrate the simultaneous measurement of 5 isotopologues of N₂O including ¹⁷O using our recently launched MGAⁱ-N₂O analyzer. Measurements of different samples, showing high stability and precision, illustrate the potential but also the limitations of this novel analyzer. In addition to continuous flow, a batch sampling mode option will be introduced and characterized.  Recent improvements in the measurement of novel tracers such as OCS and HONO, combined with up to 9 other gases in a single instrument, will also be presented.