Staff:

Dr. Bruno Glaser
(working animal)

PD Dr. Georg Guggenberger 
(project coordinator)

Dr. Wulf Amelung
(project coordinator)

Prof. Dr. Wolfgang Zech (project coordinator)

Jochen Schmitt
(Masters student)

Tanja Gonter
(Technical Assistant)
 
 

Bruno Glaser, Wulf Amelung, Georg Guggenberger und Wolfgang Zech

Lehrstuhl Bodenkunde, Universität Bayreuth, D-95440 Bayreuth. Email: bruno.glaser@uni-bayreuth.de

Rationale

The motivation for the determination of compound specific isotope ratios in humic substances is based on the fact that in soils and their chemical and physical fractions many different organic substrates for microbes exist. The analysis of stable carbon isotopes (¹²C, ¹³C) of such bulk samples results in a mean isotopic signal (d¹³C) which does not allow a differentiation between labile and stable carbon in organic compounds. To differentiate between differently available C-sources or to recognize specific pathways for the heterotrophic use of these sources, the compound specific analysis of the d¹³C-signal by means of gas chromatography - combustion - isotope ratio mass spectrometry (GC-C-IRMS) is necessary. Our approach is based on the analysis of the d¹³C-singal of biomarkers such as lignin phenols, amino acids, amino sugars and benzenecarboxylic acids in soil samples and their physical fractions. In the past two years we adapted methods developed at our institute for the quantification of the above mentioned biomarkers for the analysis of compound specific isotope ratios by means of GC-C-IRMS and identified and eliminated method induced isotope discriminations. 

Peak identity can be checked by splitting the GC-effluent and a part entering an Ion-Trap MS.