Dear Geoff,
 
you may want to read the following papers:

Glaser, B., Amelung, W. 2002. Determination of 13C natural abundance of amino acid enantiomers in soil: methodological considerations and first results. Rapid Communications in Mass Spectrometry 16, 891-898.

Schmitt, J., Glaser, B., Zech, W. 2003. Amount-dependent isotopic fractionation during compound-specific isotope analysis. Rapid Communications in Mass Spectrometry 17, 970-977.

Meier-Augenstein, W., Watt, P. W., Langhans, C. D. 1996. Influence of gas chromatographic parameters on measurement of 13C/12C isotope ratios by gas-liquid chromatography-combustion isotope ratio mass spectrometry. Journal of Chromatography A 752, 233-241.

Meier-Augenstein, W. 1997. The chromatogrphic side of isotope ratio mass spectrometry: Pitfalls and answers. LC GC International, 17-25.

 

Kind regards

 

Bruno

 

**********************************************
Dr. Bruno Glaser
Lehrstuhl für Bodenkunde und Bodengeographie
Universität Bayreuth
D-95440 Bayreuth
Deutschland
Phone: ++49-921-552254
Fax: ++49-921-552246
Email: [log in to unmask]
Web: http://www.geo.uni-bayreuth.de/bodenkunde
**************************************************

-----Ursprüngliche Nachricht-----
Von: Stable Isotope Geochemistry [mailto:[log in to unmask]]Im Auftrag von Geoffrey Garrison
Gesendet: Donnerstag, 15. Mai 2003 00:11
An: [log in to unmask]
Betreff: [ISOGEOCHEM] ISODAT problem

We recently installed a new Finnigan MAT253. After the install, we discovered that the isotopic results being reported by ISODAT were varying as a function of sample size. I would normally chalk this up to incomplete sample combustion or acidification, but these samples were coming directly from our CO2 standard tank. Finnigan has been totally unable to even suggest what the problem might be or how to pursue it. I think the problem is in how ISODAT (ver. 1.5) is processing the output from the 253, but it’s not at all clear from the manual how to troubleshoot such a problem. There is a -0.6 per mil reduction in d18O and a +0.3 per mil increase in d13C on CO2 samples from the same tank ranging between 10K mV and 40K mV in size. Any advise or tales of similar experiences would be greatly appreciated.

 

 

Thanks,

Geoff

 

 

Geoffrey Garrison, Associate Researcher

Department of Earth and Space Sciences University of Washington  
63 Johnson Hall, Box 351310

Seattle, WA  98195

(206)616-8763, office

(206)543-6327, lab

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