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Fully automated, high‐precision instrumentation for the isotopic analysis of tropospheric N 2 O using continuous flow isotope ratio mass spectrometry
Author(s) -
Potter Katherine E.,
Ono Shuhei,
Prinn Ronald G.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6623
Subject(s) - chemistry , instrumentation (computer programming) , isotope , mass spectrometry , isotope ratio mass spectrometry , analytical chemistry (journal) , isotope analysis , chromatography , radiochemistry , nuclear physics , physics , computer science , operating system , ecology , biology
RATIONALE Measurements of the isotopic composition of nitrous oxide in the troposphere have the potential to bring new information about the uncertain N 2 O budget, which mole fraction data alone have not been able to resolve. Characterizing the expected subtle variations in tropospheric N 2 O isotopic composition demands high‐precision and high‐frequency measurements. To enable useful observations of N 2 O isotopic composition in tropospheric air to reduce N 2 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 N 2 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‰ (1 σ )), 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 N 2 O air samples, with fully automated capabilities to enable high‐frequency in situ measurements. Copyright © 2013 John Wiley & Sons, Ltd.