Determination of the natural abundances of the stable isotopes of nitrogen 15 and carbon 13 by mass spectrometry a simplified manual method for the preparation of nitrogen and carbon dioxide
Handley, L.L.; Scrimgeour, C.M.; Thornton, S.F.; Sprent, J.I.
Functional Ecology 5(1): 119-124
1991
ISSN/ISBN: 0269-8463 Accession: 007195797
Small variations in the natural abundance of stable isotopes are becoming widely acknowledged as imporant in explaining both ecosystems and physiological processes, but there are considerable technical problems of sample preparation. Conflicting claims for precision also confuse the potential user. To recover both N2 and CO2 from samples of plant tissues, we use a combustion method which is simpler t han some previously described methods in that: 1 It uses a relatively low vacuum in the preparation line. 2 It uses activated charcoal for capturing N2. 3 It does not require separate freezing of CO2 and water vapour. We have overcome the problem of low N (and high C) contents of plant samples by pooling replicates of combusted samples on the vacuum line. We store and transport N2 gas in sealed glass tubes. These modifications simplify previously described methods without sacrificing precision.