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We use a simple custom built manifold for prepping samples for the Gas Bench. We’ve been using this for several years now and found it be simple, robust, and fast (14 samples in ~10 minutes). Undergraduates can prepare their own samples without risk of damaging the system (such as getting acid on the septa and up the capillary).

The manifold is described here:

http://minerva.union.edu/gillikid/manifold.htm

Cheers
Dave
_____________________________________________________________________
David P. Gillikin, Ph.D.
Professor of Geology
Director: Environmental Science, Policy & Engineering Program and 
Union College Stable Isotope Laboratory
Union College
Department of Geology
807 Union St.
Schenectady, NY 12308

Office phone: (518) 388-6679
Lab phone:     (518) 388-8741
email:  [log in to unmask]
web: http://minerva.union.edu/gillikid/
Lab Website: http://minerva.union.edu/gillikid/lab.htm
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On Dec 7, 2018, at 9:39 AM, Geldern, Robert van <[log in to unmask]> wrote:

Wolfram,

in this setup -> would’t the space between the FS capillary and the surrounding needle (your point 4) already work as a “relief needle”?
So, do you really need a second needle for the outflow (your point 5)?

regards,
Robert


Am 07.12.2018 um 15:24 schrieb Wolfram Meier-Augenstein (pals) <[log in to unmask]>:

Hi Bob,


Similar to what Robert has described and suggested, our off-line, manual purge procedure worked like this.

1. Weigh out samples into containers for digest, e.g. exetainers (or vacutainers) and close lids.
2. Line up containers in a test tube holder or similar.
3. Connect N2 cylinder via 1/16" SS tubing, needle valve and reducing union to a piece of uncoated megabore fused silica capillary. Adjust needle valve for an N2 flow rate of approx. 2 ml/min.
4. Thread megabore capillary through a disposable syringe needle of sufficiently wide gauge (18 if memory serves).
5. Insert "relieve" needle (e.g. 26 gauge but almost any gauge will do) through container septum (stopper).
6. Insert needle-megabore capillary combo through container septum (stopper); feed megabore through needle until approx. 2/3 down the container.
7. Open regulator on N2 line (carefully).
8. Depending on the net volume of your container it will take 6+ minutes at the above flow rate to purge.
9. Remove needles, move on to the next container and repeat.


Best,

Wolfram



-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Michener, Robert H
Sent: 07 December 2018 13:58
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] couple of carbonate questions

Thanks for all the comments! I thought I'd simplify things with a glove bag, but I'm probably causing more problems. A separate flushing line would be useful, so Robert, if it's easy, the photos would be helpful. I didn’t think argon would work but since it's in the lab I thought I'd check.

For this set, it's probably best to just use the MultiFlow to flush the vials. But thanks for all the insight and help!

Bob


***********
Robert Michener
IRMS Laboratory Manager
Boston University Stable Isotope Laboratory Department of Biology
5 Cummington Mall
Boston, MA  02215

Voice: 617-353-6980
Fax: 617-353-6340
Email: [log in to unmask]
Website:  www.bu.edu/sil/
"You are what you eat, plus a few permil!"
***********

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Geldern, Robert van
Sent: Thursday, December 6, 2018 2:41 PM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] couple of carbonate questions

I agree with Wolfgang.

Glove Box: I don’t know. Never tried. What about a device that flushes one or more vials offline directly from a gas bottle with a needle valve in between to regulate the flow? I have no direct drawings but I might dig out some fotos.

Flushing gas: Ar was discussed here on Isogechem several times (mainly during every He “crisis”). When I recall this correctly, this was not the gas you want to have in your IRMS. N2 works. I can dig out some screenshots where I used He and N2 as flushing gas for identical samples and check for offsets. The offset was not zero, but within “acceptable" limits (depending of course on your research question). The main issue is the air peak that you generate (NO2 gas that interferes on m/z46). In a Thermo Gasbench system you must “blank” this peak, that comes right before your CO2 peak, by a clever on/off setup of your open split settings (open split connects the preparation device to the IRMS; no idea about the MultiFlow).

regards,
Robert



Am 06.12.2018 um 19:49 schrieb Wolfram Meier-Augenstein (pals) <[log in to unmask]>:

Hi Bob,


No idea if the glove box idea would work, but I would strongly advise against using Ar to purge the vials. Dry, zero-grade N2 is the better option.

Contemporaneous presence of Argon in the IRMS ion source will suppress / interfer with ionization of CO2 resulting in skewed d13C values. I have described this phenomenon with illustrating figure in Part II of my book (chapter II.4.2).


Best,

Wolfram


******************************************************
Prof. Dr W Meier-Augenstein, CChem, FRSC Stable Isotope Forensics &
Analytical Sciences

Robert Gordon University
School of Pharmacy and Life Sciences
The Ian Wood Building
Garthdee Road
Aberdeen
AB10 7GJ

E-mail:   [log in to unmask]

https://onlinelibrary.wiley.com/doi/book/10.1002/9781119080190
________________________________
From: Stable Isotope Geochemistry <[log in to unmask]> on behalf
of Michener, Robert H <[log in to unmask]>
Sent: 06 December 2018 17:39:03
To: [log in to unmask]
Subject: [ISOGEOCHEM] couple of carbonate questions

Hi all,

I'm hoping to get started with some backlogged carbonate samples. We have a MultiFlow to flush the vials, but to save time I'm thinking of flushing the vials in a glove bag. Has anyone tried this? And would argon work as a flush gas (I have a tank on hand)?

Thanks,

Bob


***********
Robert Michener
IRMS Laboratory Manager
Boston University Stable Isotope Laboratory Department of Biology
5 Cummington Mall
Boston, MA  02215

Voice: 617-353-6980
Fax: 617-353-6340
Email: [log in to unmask]<mailto:[log in to unmask]>
Website:  www.bu.edu/sil/
"You are what you eat, plus a few permil!"
***********





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