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Determination of 15 N in 15 N‐enriched nitrite and nitrate in aqueous samples by reaction continuous flow quadrupole mass spectrometry
Author(s) -
Russow Rolf
Publication year - 1999
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/(sici)1097-0231(19990715)13:13<1334::aid-rcm606>3.0.co;2-c
Subject(s) - chemistry , nitrate , nitrite , mass spectrometry , aqueous solution , quadrupole , chromatography , continuous flow , analytical chemistry (journal) , organic chemistry , biochemical engineering , physics , atomic physics , engineering
The 15 N tracer method is the most suitable method for studying complex N transformation processes in microbiology and biochemistry. It entails the constant determination of the 15 N abundance of the inorganic nitrogen (N) compounds nitrite and nitrate. However, 15 N analytical methods are time‐consuming, difficult to automate, and require at least 10 µg of N per determination. An additional obstacle in the case of nitrite is that it usually only occurs in very small amounts (ppb) dwarfed by much larger quantities of nitrate (ppm). More useful is an approach in which the N compound is selectively converted into a gaseous form suitable for direct measurement by mass spectrometry. By using this ‘reaction continuous‐flow mass spectrometry’ (R/CFMS) we developed methods for the 15 N determination of nitrite and nitrate from tracer experiment samples, i.e. artificially enriched in 15 N. Because both methods are based on the same principle, one continuous flow setup connected directly to a quadrupole mass spectrometer for all determinations was used. Nitrite and nitrate are reduced to NO by iodide and titanium(III) chloride, respectively. The technique developed ensures a precision of relative standard deviation ≤3% if at least 0.5 and 2 µg N with an abundance of ≥1 at.% are to be measured for nitrite and nitrate, respectively. Copyright © 1999 John Wiley & Sons, Ltd.