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Dear Isogeochemists

Just an update and to say thank you for all the suggestions.

I kept everything as is but replaced all my stainless steel with teflon and now I go through about 5 scrub samples and combustions are beautiful and no tail.

Thanks again.

Cheers
Darren




Dr Darren Grocke
Department of Earth Sciences
Durham University
South Road
Durham
County Durham
DH1 3LE
UK

https://scholar.google.co.uk/citations?user=kYv6BFcAAAAJ&hl=en
@GrockeSIBL


On 16 Jul 2019, at 06:11, Anette Giesemann <[log in to unmask]> wrote:

Hi Darren,

have you tried Sicapent as drying agent instead of Magnesiumperchlorate? It consists of  Phosphorpentoxide on a carrier and comes with an indicator. We found it to be a lot more efficient than Magnesiumperchlorate and a lot easier to handle than pure Phosphorpentoxide.
We had 80°C for a short separation column and found that with our system 60° was ok. 700 sec is what we need as well for a proper run..
One thing I forgot to mention is, that we exchanged all connections etc that were of stainless steel to Teflon to not loose S through adsorbtion on the walls of capillaries etc.

Regards
Anette


__________________________________________________________________________________________________

Dr. Anette Giesemann
Leitung IRMS-Labor
Thünen-Institut für Agrarklimaschutz
Bundesallee 65
D-38116 Braunschweig

Tel.:      +49 531 596-2538
Fax:     +49 531 596-2699
E-Mail: [log in to unmask]
Web   : www.thuenen.de

Das Johann Heinrich von Thünen-Institut, Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei – kurz: Thünen-Institut – besteht aus 14 Fachinstituten,
die in den Bereichen Ökonomie, Ökologie und Technologie forschen und die Politik beraten.


Von: "GROCKE, DARREN R." <[log in to unmask]>
An: "Anette Giesemann" <[log in to unmask]>
Gesendet: Montag, 15. Juli 2019 16:16:36
Betreff: Re: [ISOGEOCHEM] New column and sulphur

Dear Anette

Thanks for the email.

I use a magnesium perchlorate water trap.

I have not tried elemental sulphur - I will give that a bash tonight.

When I have lowered the GC temperature it often takes a lot longer to analyse a sequence, so I found that 89 is an optimum temperature to separate CO2 and SO2, but maintain good peaks and a reasonable run time (700 seconds).

Cheers
Darren



On 15 Jul 2019, at 14:05, Anette Giesemann <[log in to unmask]> wrote:

Dear Darren,

yes,this is absolutely normal. It didn't change for more than 30 years.
It always takes several samples to condition the column and saturate all surfaces with SO2.
Have you ever tried to combust elemental sulfur? Its pure sulfur that passes the column then.
Years ago, we used it. But you should take care of the isotopic composition of what you use for saturation as SO2 exchanges readily with sulfur from inside the system.

Another thing: what kind of water trap are you using?
My experience is, that wherever the tiniest bit of water is in the system, sulfuric acid is produced and you loose S on its way through the EA.

With respect to tailing: what temperature do you use in the column? We used about 60 °C  - a lot warmer than for CO2.

Hope this helps.
Regards
Anette

__________________________________________________________________________________________________

Dr. Anette Giesemann
Leitung IRMS-Labor
Thünen-Institut für Agrarklimaschutz
Bundesallee 65
D-38116 Braunschweig

Tel.:      +49 531 596-2538
Fax:     +49 531 596-2699
E-Mail: [log in to unmask]
Web   : www.thuenen.de

Das Johann Heinrich von Thünen-Institut, Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei – kurz: Thünen-Institut – besteht aus 14 Fachinstituten,
die in den Bereichen Ökonomie, Ökologie und Technologie forschen und die Politik beraten.


Von: "GROCKE, DARREN R." <[log in to unmask]>
An: "Stable Isotope Geochemistry" <[log in to unmask]>
Gesendet: Montag, 15. Juli 2019 14:07:20
Betreff: [ISOGEOCHEM] New column and sulphur

Dear Colleagues

I have been running sulphur isotopes now for over a year now, using a Delta V+ mass spec with a Costech EA, but I find that when I put in a new reaction column I need to put through about 30-50 sulphanilamide sample before I start getting good signals, no tailing etc.

Does anyone know how I can reduce the number of conditioning samples before running standards and samples?

I’d like to know other experiences you have, or is this just the norm and I need to expect this with doing sulphur isotope analyses.

Cheers
Darren




Dr Darren Grocke
Department of Earth Sciences
Durham University
South Road
Durham
County Durham
DH1 3LE
UK

https://scholar.google.co.uk/citations?user=kYv6BFcAAAAJ&hl=en
@GrockeSIBL