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Stable Isotope Geochemistry

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Subject:
From:
Dr W Meier-Augenstein <[log in to unmask]>
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Date:
Tue, 24 Feb 2004 08:05:46 -0000
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Hi Hil and others,


I didn't want to open a can of worms in my previous reply but since the
discussion has move on and touched on the subject...

I'm not too great a fan of MolSieve 5A columns (whatever the size, shape
or form) since this stationary phase causes huge mass discrimination for
CO2 even if one achieves complete elution in one peak of acceptable
shape.


Cheers,

Wolfram



> -----Original Message-----
> From: Stable Isotope Geochemistry
> [mailto:[log in to unmask]] On Behalf Of Hilary Stuart-Williams
> Sent: 24 February 2004 03:01
> To: [log in to unmask]
> Subject: Re: What GC column for CO separation?
>
>
> Thanks Toti
>
> Could I have a copy of the application notes?
>
> Now there's a good question about the CO2!
>
> Yes, it does come off, as rather a blurred peak at 1000
> seconds under our conditions.  So, if you do a 600 second
> run, your CO2 comes off RIGHT in the tail of your CO.  And
> although the amplitude is very small after scrubbing, the
> dissociation in the source causes some wild values.  But even
> without the CO2 -> CO+O fractionation, the gas comes from the
> PREVIOUS sample.
>
> So you have to scrub VERY well or do long runs.  And the CO2
> doesn't have enough amplitude (from our set up) to show on
> anything apart from the ratio traces.  And then only for
> about 1 in 20 samples ...
>
> Hil
>
> .
>

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