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Rapid Commun Mass Spectrom. 2010 Dec 30;24(24):3615-23. doi: 10.1002/rcm.4798.

A suite of sensitive chemical methods to determine the δ15N of ammonium, nitrate and total dissolved N in soil extracts.

Author information

1
Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.

Abstract

Natural (15) N abundances (δ(15) N values) of different soil nitrogen pools deliver crucial information on the soil N cycle for the analysis of biogeochemical processes. Here we report on a complete suite of methods for sensitive δ(15) N analysis in soil extracts. A combined chemical reaction of vanadium(III) chloride (VCl(3) ) and sodium azide under acidic conditions is used to convert nitrate into N(2) O, which is subsequently analyzed by purge-and-trap isotope ratio mass spectrometry (PTIRMS) with a cryo-focusing unit. Coupled with preparation steps (microdiffusion for collection of ammonium, alkaline persulfate oxidation to convert total dissolved N (TDN) or ammonium into nitrate) this allows the determination of the δ(15) N values of nitrate, ammonium and total dissolved N (dissolved organic N, microbial biomass N) in soil extracts with the same basic protocol. The limits of quantification for δ(15) N analysis with a precision of 0.5‰ were 12.4 µM for ammonium, 23.7 µM for TDN, 16.5 µM for nitrate and 22.7 µM for nitrite.

PMID:
21080513
DOI:
10.1002/rcm.4798
[Indexed for MEDLINE]

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