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Equations for Determination of Nitrogen‐15 Labeled Dinitrogen and Nitrous Oxide by Mass Spectrometry
Author(s) -
Mulvaney R. L.,
Boast C. W.
Publication year - 1986
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1986.03615995005000020021x
Subject(s) - calculator , fraction (chemistry) , mass spectrometry , mole fraction , nitrous oxide , chemistry , mass fraction , nitrogen , oxide , analytical chemistry (journal) , computer science , environmental chemistry , chromatography , organic chemistry , operating system
In mass spectrometric procedures recently developed for determination of 15 N‐labeled dinitrogen (N 2 ) and nitrous oxide (N 2 O) evolved from soils, calculations are performed to determine the mole fraction of 15 N in the N pool from which this N 2 or N 2 O was derived ( 15 X N ), and a fraction proportional to the amount evolved ( d ). The equations originally derived for these calculations are based on several approximations and are so simple that they can easily be performed using a handheld calculator. Modern ratio mass spectrometers are usually equipped with an on‐line programmable calculator or computer to process the digital output from the integrating ratiometer, which has made it practical to calculate 15 X N and d using equations based on fewer approximations than the equations previously derived. Refined versions of the equations are derived in this paper. The refined equations are much more complicated than the original equations, but they are more accurate and permit the use of fertilizers containing <20 atom % 15 N in studies of denitrification.