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Nitrogen and triple oxygen isotopes in near‐road air samples using chemical conversion and thermal decomposition
Author(s) -
Smirnoff Anna,
Savard Martine M.,
Vet Robert,
Simard MarieChristine
Publication year - 2012
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.6406
Subject(s) - chemistry , nitrogen , nitrite , nitrate , ammonia , isotopes of nitrogen , environmental chemistry , ammonium nitrate , ammonium , analytical chemistry (journal) , nitrous oxide , decomposition , isotope ratio mass spectrometry , mass spectrometry , chromatography , organic chemistry
RATIONALE The determination of triple oxygen (δ 18 O and δ 17 O) and nitrogen isotopes (δ 15 N) is important when investigating the sources and atmospheric paths of nitrate and nitrite. To fully understand the atmospheric contribution into the terrestrial nitrogen cycle, it is crucial to determine the δ 15 N values of oxidised and reduced nitrogen species in precipitation and dry deposition. METHODS In an attempt to further develop non‐biotic methods and avoid expensive modifications of the gas‐equilibration system, we have combined and modified sample preparation procedures and analytical setups used by other researchers. We first chemically converted NO 3 – and NH 4 + into NO 2 – and then into N 2 O. Subsequently, the resulting gas was decomposed into N 2 and O 2 and analyzed by isotope ratio mass spectrometry (IRMS) using a pre‐concentration system equipped with a gold reduction furnace. RESULTS The δ 17 O, δ 18 O and δ 15 N values of nitrate and nitrite samples were acquired simultaneously in one run using a single analytical system. Most importantly, the entire spectrum of δ 17 O, δ 18 O and/or δ 15 N values was determined from atmospheric nitrate, nitric oxide, ammonia and ammonium. The obtained isotopic values for air and precipitation samples were in good agreement with those from previous studies. CONCLUSIONS We have further advanced chemical approaches to sample preparation and isotope analyses of nitrogen‐bearing compounds. The proposed methods are inexpensive and easily adaptable to a wide range of laboratory conditions. This will substantially contribute to further studies on sources and pathways of nitrate, nitrite and ammonium in terrestrial nitrogen cycling. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.