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A portable automated system for trace gas sampling in the field and stable isotope analysis in the laboratory
Author(s) -
Theis Daniel E.,
Saurer Matthias,
Blum Herbert,
Frossard Emmanuel,
Siegwolf Rolf T. W.
Publication year - 2004
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.1596
Subject(s) - chemistry , sampling (signal processing) , trace gas , analytical chemistry (journal) , stable isotope ratio , isotopes of carbon , isotope , isotope analysis , mineralogy , environmental chemistry , geology , total organic carbon , physics , organic chemistry , quantum mechanics , oceanography , detector , optics
A computer‐controllable mobile system is presented which enables the automatic collection of 33 air samples in the field and the subsequent analysis for δ 13 C and δ 18 O stable isotope ratios of a carbon‐containing trace gas in the laboratory, e.g. CO 2 , CO or CH 4 . The system includes a manifold gas source input for profile sampling and an infrared gas analyzer for in situ CO 2 concentration measurements. Measurements of δ 13 C and δ 18 O of all 33 samples can run unattended and take less than six hours for CO 2 . Laboratory tests with three gases (compressed air with different p CO2 and stable isotope compositions) showed a measurement precision of 0.03‰ for δ 13 C and 0.02‰ for δ 18 O of CO 2 (standard error (SE), n = 11). A field test of our system, in which 66 air samples were collected within a 24‐hour period above grassland, showed a correlation of 0.99 (r 2 ) between the inverse of p CO 2 and δ 13 C of CO 2 . Storage of samples until analysis is possible for about 1 week; this can be an important factor for sampling in remote areas. A wider range of applications in the field is open with our system, since sampling and analysis of CO and CH 4 for stable isotope composition is also possible. Samples of compressed air had a measurement precision (SE, n = 33) of 0.03‰ for δ 13 C and of 0.04‰ for δ 18 O on CO and of 0.07‰ for δ 13 C on CH 4 . Our system should therefore further facilitate research of trace gases in the context of the carbon cycle in the field, and opens many other possible applications with carbon‐ and possibly non‐carbon‐containing trace gases. Copyright © 2004 John Wiley & Sons, Ltd.