Stable Isotope Geochemistry


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Jennifer McKay <[log in to unmask]>
Reply To:
Stable Isotope Geochemistry <[log in to unmask]>
Thu, 1 Sep 2005 08:37:19 -0500
text/plain (83 lines)
Hi David,

We do use the foam insulation, but have punched out small holes 
(~0.8cm) at each vial position to give the needle a clear path to the 
vial.  We use the Aquaprep needle from GV.  So far no clogging 
problems, but we don't use the Kel-F's when running H.  We've been 
getting good results using the Labco vials with the gray septa.  I 
also use this type of vial (without Kel-F's) for CO2 analysis using 
our Microgas.  The only time we use Kel-F's (and the blue silicone 
septa) is when we are analyzing carbonates using the Mulitcarb. 
Lastly, we do not reuse the septa (either the gray ones or the blue 
silicone ones).

I hope this helps.

>I've been trying to do hydrogen in water by equilibration on our 
>PrismIII with a multiprep.  I am having trouble getting consistantly 
>good results.  I have 4 questions.
>1)  Does anyone use the foam insulation on top of the sample holder? 
>I'm finding it causes needles to bend.
>2)  What sort of needle do others use (diameter, type of tip)? 
>Since I bent the needle I had been using for ages (for oxygen in 
>water) I've had a lot of problems with the replacement needle 
>clogging.  It is getting a clear plastic (presumably Kel-F) in the 
>tip of the needle.
>3)  What function does the Kel-F septum perform?  Once the vial has 
>been filled there is a hole in the Kel-F sepum which allows the gas 
>to be in contact with the silicone septum.
>4)  Can you reuse the silicone rubber septa and how often?  The 
>manual says you can reuse them a few times but I'm beginning to 
>wonder whether they are leaking.
>Any advice or insights will be most welcome.
>David Wheeler
>Professional Officer
>Geochemistry Laboratory
>School of Earth and Environmental Sciences
>University of Wollongong,
>Wollongong, 2522, NSW
>Phone   02 4221 4586 (office)
>	02 4226 5903 (lab)
>Fax 	02 4221 4250
>E-mail	[log in to unmask]
>'Oh no, we won't give in,
> we'll go living in the past'

Jennifer Mckay
Agente de Recherche / Research Associate
GEOTOP - Universite du Quebec a Montreal
C.P. 8888, succursale Centre-Ville
Montreal, Quebec, Canada
H3C 3P8

Telephone bureau/office: 514-987-3000 (poste/ext 2413)
Telephone lab: 514-987-3000 (poste/ext 7028)
Telephone GEOTOP: 514-987-4080
Telecopieur/Fax: 514-987-3635
E-mail: [log in to unmask] or if that fails try [log in to unmask]