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Methods to adjust for the interference of N 2 O on δ 13 C and δ 18 O measurements of CO 2 from soil mineralization
Author(s) -
Beheydt D.,
Boeckx P.,
Clough T. J.,
Vermeulen J.,
Sherlock R. R.,
Van Cleemput O.
Publication year - 2005
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.1907
Subject(s) - chemistry , analytical chemistry (journal) , standard deviation , isotope , mass spectrometry , stable isotope ratio , trace gas , chromatography , nuclear physics , physics , mathematics , organic chemistry , statistics
In this paper we present an overview of the present knowledge relating to methods that avoid interference of N 2 O on δ 13 C and δ 18 O measurements of CO 2 . The main focus of research to date has been on atmospheric samples. However, N 2 O is predominantly generated by soil processes. Isotope analyses related to soil trace gas emissions are often performed with continuous flow isotope ratio mass spectrometers, which do not necessarily have the high precision needed for atmospheric research. However, it was shown by using laboratory and field samples that a correction to obtain reliable δ 13 C and δ 18 O values is also required for a commercial continuous flow isotope ratio mass spectrometer. The capillary gas chromatography column of the original equipment was changed to a packed Porapak Q column. This adaptation resulted in an improved accuracy and precision of δ 13 C (standard deviation Ghent : from 0.2 to 0.08‰; standard deviation Lincoln : from 0.2 to 0.13‰) of CO 2 for N 2 O/CO 2 ratios up to 0.1. For δ 18 O there was an improvement for the standard deviation measured at Ghent University (0.13 to 0.08‰) but not for the measurements at Lincoln University (0.08 to 0.23‰). The benefits of using the packed Porapak Q column compared with the theoretical correction method meant that samples were not limited to small N 2 O concentrations, they did not require an extra N 2 O concentration measurement, and measurements were independent of the variable isotopic composition of N 2 O from soil. Copyright © 2005 John Wiley & Sons, Ltd.