Fully automated, high-precision instrumentation for the isotopic analysis of tropospheric N<sub>2</sub>O using continuous flow isotope ratio mass spectrometry.

TitleFully automated, high-precision instrumentation for the isotopic analysis of tropospheric N2O using continuous flow isotope ratio mass spectrometry.
Publication TypeMiscellaneous
Year of Publication2013
AuthorsPotter KE, Ono S, Prinn RG
Accession Number23821566
Abstract

RATIONALE: Measurements of the isotopic composition of nitrous oxide in the troposphere have the potential to bring new information about the uncertain N2 O budget, which mole fraction data alone have not been able to resolve. Characterizing the expected subtle variations in tropospheric N2 O isotopic composition demands high-precision and high-frequency measurements. To enable useful observations of N2 O isotopic composition in tropospheric air to reduce N2 O source and sink uncertainty, it was necessary to develop a high-precision measurement system with fully automated capabilities for autonomous deployment at remote research stations. METHODS: A fully automated pre-concentration system for high-precision measurements of N2 O isotopic composition (δ(15) N(β) , δ(15) N(α) , δ(18) O) in tropospheric air has been developed which combines a custom liquid-cryogen-free cryo-trapping system and gas chromatograph interfaced to a continuous flow isotope ratio mass spectrometry (IRMS) system. A quadrupole mass spectrometer was coupled in parallel to the IRMS system during development to evaluate peak interference. Multi-port inlet and fully-automated capabilities allow streamlined analyses between in situ air inlet, air standards, flask air sample, or other gas source in exactly replicated analysis sequences. RESULTS: The system has the highest precision to date for (15) N site-specific composition results (δ(15) N(α) ±0.11‰, δ(15) N(β) ±0.14‰ (1σ)), attributed mostly to uniformity of analytical cycles and particular attention to fluorocarbon interference noted for (15) N site-specific measurements by IRMS. Air measurements demonstrated the fully automated capacity and performance. CONCLUSIONS: The system makes substantial headway in measurement precision, possibly defining the limits of IRMS measurement capabilities in low concentration N2 O air samples, with fully automated capabilities to enable high-frequency in situ measurements. Copyright © 2013 John Wiley & Sons, Ltd.

URLhttp://www.ncbi.nlm.nih.gov/pubmed/23821566