Dear Dachun,
There is quite some material published that gives you a good
indication what kind of equilibrium times to expect. But of course
everything depends on the geometry of you equilibrium vessel, and on
the precision that you are aiming at.
So my advice: try it out! That is really simple: just equilibrate
under your working conditions samples of the same water fo 1,2,3,4,5,
etc hours (preferably in triplo for each time) and see what happens !
good luck,
Harro
>Dachun,
>
>In my experience not just the salt content but also the amount of water can
>make a difference. I do equilibrations at room temperature in Exetainer
>vials with a 0.2% CO2 headspace. Whereas 500 uL equilibrates easily in 2
>days at room temperature (21-23C), 2 drops of water, about 20 uL, takes 5
>days. So I would carefully consider the sample volume as well.
>
>We had discovered early on that we get more throughput on our Thermo Gas
>Bench by having a production line of sample tubes plus standards set out in
>the lab equilibrating, and then after 2-5 days just putting them in the
>sampler. Using 25 psi on the Gas Bench we can run 132 tubes in 23
>hours. Even with extensive standards it is therefore easy to run 84
>unknowns a day, every day by letting them equilibrate at room temperature,
>then putting the entire set onto the sampler.
>
>Hope this helps.
>
>Paul Brooks.
>
>
>
>
>
>At 02:21 PM 10/8/04 -0400, you wrote:
>><?xml version="1.0" ?>
>>Hi Dachun,
>>the following paper is not specifically on temperature variations but
>>chemistry (salt content) but does have equilibration times.
>>FRITZ, P.; FRAPE, S.K.; DRIMMIE, R.J.; and HEEMSKERK, A.R.-1986-Reply to
>>comments by Grabczak et al on "Water-Rock Interaction and
>>Chemistry of Groundwaters from the Canadian Shield."
>>Geochemica. Cosmochemica. Acta. 50, pp 1561-1563.
>>regards
>>Rick
>>On 8 Oct 2004 at 10:52, Dachun Zhang wrote:
>>Dear all:
>>
>>Is there any research paper on the equilibration time of CO2-H2O system at
>>different temperatures? I'd like to know if five hours are sufficient at
>>40 oC.
>>
>>Dachun Zhang
>>A. Richard Heemskerk [log in to unmask]
>>Environmental Isotope Laboratory Telephone: 519-888-4567
>>Department of Earth Sciences Extension: 5838
>>University of Waterloo Facsimile: 519-746-7484
>>Waterloo, Ontario, Canada N2L 3G1
>>http://sciborg.uwaterloo.ca/research_groups/eilab
>
>
>
>Paul D. Brooks,
>Center for Stable Isotope Biogeochemistry,
>Dept. Integrative Biology MC3140,
>3060 Valley Life Sciences Building,
>UC Berkeley, Ca. 94720-3140.
>
>[log in to unmask]
>
>phone (510)643-1748,
>FAX (510)643-1749
>
>http://ib.berkeley.edu/groups/biogeochemistry/
--
Prof. dr. Harro A.J. Meijer
Centrum voor IsotopenOnderzoek (CIO), Rijksuniversiteit Groningen
Nijenborgh 4, 9747 AG Groningen, Netherlands
tel +31-50-3634760 fax +31-50-3634738
http://www.rug.nl/cio
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