Isotopically characterised N₂O reference materials for use as community standards

Abstract

Rationale: Information on the isotopic composition of nitrous oxide (N 2 O) at natural abundance supports the identification of its source and sink processes. In recent years, a number of mass spectrometric and laser spectroscopic techniques have been developed and are increasingly used by the research community. Advances in this active research area, however, critically depend on the availability of suitable N 2 O isotope Reference Materials (RMs).Methods: Within the project Metrology for Stable Isotope Reference Standards (SIRS), seven pure N 2 O isotope RMs have been developed and their 15 N/ 14 N, 18 O/ 16 O, 17 O/ 16 O ratios and 15 N site preference (SP) have been analysed by specialised laboratories against isotope reference materials. A particular focus was on the 15 N site-specific isotopic composition, as this measurand is both highly diagnostic for source appointment and challenging to analyse and link to existing scales.

Forensic Discrimination of Smokeless Powders Using Carbon and Nitrogen Isotope Ratios

“…All samples and replicates (both BSIA and CSIA) were measured via a Thermo Fisher Scientific elemental analyzer IsoLink peripheral device connected to a Thermo Fisher Scientific Delta V Plus IRMS for C and N isotopes. Specifically, in this method, the EA was run without the addition of oxygen gas; thus thermal decomposition of the samples occurred instead of “traditional” combustion. ,− This was possible due to the nature of explosives and explosive components containing fuel to oxidizer ratios facilitating quantitative conversion to gas without requiring supplemental oxygen …”

Hydrologic Connectivity Regulates Riverine N2O Sources and Dynamics

“…The isotope ratios of dissolved N 2 O were measured using a custom-built autosampler coupled with a purge-and-trap isotope ratio mass spectrometer (IRMS) (Elementar Isorpime precION, Germany). We followed the method outlined by Kelly et al 28 to correct and calibrate N 2 O isotope ratios using two reference materials (USGS52 29 and RM3A 30 ) and an IRMS N 2 O reference gas, which was calibrated by Karen Casciotti (Stanford University). The 15 N/ 14 N and 18 O/ 16 O ratios of N 2 O were expressed in δ notation, defined as δ 15 N or δ 18 O = (R sample /R standard − 1) × 1000, where R standard for δ 15 N is the 15 N/ 14 N ratio of air and R standard for δ 18 O is the 18 O/ 16 O ratio of Vienna Standard Mean Ocean Water (VSMOW).…”