Print

Print


Hi Gavin,


My apologies, in my response to Fred's enquiry I should have pointed him towards the papers by members of Tom Brenna's group also (Goodman, Sacks, Tobias), and of course the work by Dawn Merritt.

Don't you just hate pre-senile dementia creeping up on you?


Best wishes,

Wolfram

****************************************
"Facts do not cease to exist because they are ignored."
Aldous Huxley, "Proper Studies", 1927 
****************************************
Dr W Meier-Augenstein, CChem, FRSC
Principal Scientist - Stable Isotopes
The James Hutton Institute
http://www.hutton.ac.uk 

Head of Mylnefield Isotope Signatures 
http://www.isotopesignatures.co.uk 

Director of FIRMS plc
http://www.forensic-isotopes.org/

Stable Isotope Forensics book:
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470517050.html

E-mail: [log in to unmask]
Tel.: +44 (0)1382 568781
Fax: +44 (0)1382 568544

Attention 
This message contains privileged and confidential information intended for the addressee(s) only. If this message was sent to you in error, you must not disseminate, copy or take any action in reliance on it and we request that you notify the sender immediately by return email. 

Opinions expressed in this message and any attachments are not necessarily those held by JHI or any person connected with the organisation, save those by whom the opinions were expressed.

 


-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Gavin Sacks
Sent: 04 May 2011 20:47
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] GC-IRMS, peak shape and how it affect stable isotope ratios for carbon and hydrogen

Hi Fred, in addition to Wolfram's papers, there's a couple of other papers that have looked at peak size, combustion conditions, and background.  The effects of peak shape (tailing/fronting), to my knowledge, has not been systematically studied for a given amount of material on column (say, by changing phase ratio).  My experience has been that overloading doesn't compromise d13C linearity so long as baseline resolution is still achieved . . . which is a big "if".  Most of the work is on d13C, not D/H.

Goodman and Brenna, J Chrom A 1995 (discussion of peak size) Merritt and Hayes, 1994 An. Chem Merritt and Hayes, 1995 An Chem (discusses effects of incomplete oxidation, among other things) Wolfram's 1996 J Chrom A paper and his other refs.
Sacks, Zhang, and Brenna, 2007, An Chem (buried in the discussion is a section on the role of peak width and background noise in compromising
precision)

As I've said in other posts, reproducibly defining the background is usually the main issue with getting good precision.

- Gavin

> Dear IsoGeochem
>
>  
>
> I have very difficult to find literature that concerns the subject of 
> the quality of the chromatography and how it affects the stable 
> isotope ratios in GC-IRMS.
>
> I'm thinking especially about peak shape (tailing/fronting, overload, 
> poor oxidation/reduction of oven, leakages, bad column etc), and not 
> so much about poor separation.
>
>  
>
> Has anyone on this list done studies into this subject, that could 
> tell me a little about it, or maybe show some data on it? How does 
> peak shape, background and signal strength correlate and affect the 
> isotope ratios?
>
>  
>
> Thank you very much!
>
>  
>
> Best regards,
>
> Fred Martin Kaaby
>


--
Gavin Sacks
Assistant Professor of Enology

Dept. of Food Science & Technology
NYS Ag. Experiment Station
Cornell University
Geneva, NY 14456

315-787-2458 (w)
607-592-1504 (c)
________________________________________________________
This email is from The James Hutton Institute (JHI), however the views
expressed by the sender are not necessarily the views of JHI and its
subsidiaries. This email and any attachments are confidential and are intended
solely for the use of the recipient(s) to whom they are addressed.  If you
are not the intended recipient, you should not read, copy, disclose or rely on
any information contained in this email, and we would ask you to contact the
sender immediately and delete the email from your system.  Although JHI has
taken reasonable precautions to ensure no viruses are present in this email,
neither the Institute nor the sender accepts any responsibility for any
viruses, and it is your responsibility to scan the email and any attachments.

The James Hutton Institute is a Scottish charitable company limited by
guarantee.
Registered in Edinburgh No. SC374831
Registered Office: The James Hutton Institute, Invergowrie Dundee DD2 5DA.
Charity No. SC041796