A relatively simple flush line with multiple injection ports can be
built using tubing , valves, and elbow, T, and cross connectors. You
also need a He tank with a regulator and a flowmeter. You will have to
find a suitable needle to put at the end of each branch and to make
sure there are no leaks. You could start with just one needle at the
end of the tubing and see how it works. During flushing there are two
needles inserted in the vial at the edges of the septum: the one
bringing in He and the venting one, which is unattached to any tubing.
I leave the central portion of the septum untouched for the sampling
needle during regular analysis. Then I would 1) experiment with
various flow rates and flush times on empty vials until no air shows
up in the chromatogram and 2) run a few test carbonate samples to make
sure the method finally works.
I like the off-line flush-fill method because you can flush gently
tilted vials with the acid drops sitting nicely on the walls of the
vial. Then you just straighten the vials and I think it takes about
9-10 minutes for the drop to reach the carbonate powder at the bottom.
The main problems I encountered were making the line leakproof,
finding the optimal He flow and flush time, and knowing how to
synchronize the extraction of the venting needle with stoping the He
flow in order to avoid both overpressure and loss of He . You also
could ask Gilles about building the flush line because in his lab they
experimented with various tubing materials and He flow rates. Cheers.
Mihai Lefticariu (Southern Illinois University Carbondale).
On Mon, Mar 4, 2013 at 10:11 AM, Lambert, Joe <[log in to unmask]> wrote:
> Hi all,
> Has anyone developed an off-line method for flushing a full batch (96) of exetainers? I am unsure of the cost of a stand alone CTC Analytics PAL autosampler. It would be great to free up the Gasbench-IRMS for only measurements and let the exetainers/tubes be prepped separately. Any thoughts?
> W. Joe Lambert, PhD
> 2003 Bevill Building
> Department of Geological Sciences
> The University of Alabama
> Tuscaloosa, AL 35487
> Phone (205) 348-4404
> Fax (205) 348-0818