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Stable Isotope Geochemistry

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From:
"Dr. Anette Giesemann" <[log in to unmask]>
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Date:
Thu, 7 Jul 2005 09:27:07 +0100
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Dear Irene and others,

we have been cleaning our source for years using the "scrape things off"
method for ceramics, which is time consuming. So I was very happy to
read that just baking out the ceramics is fine.

Yesterday, we followed the procedure mentioned and the result was a
mess !!!!
Several parts of the ceramics stuck to the crucible and couldn't be
removed, some had ceramics on them when we finally happened to get
them off, the quartz rings were broken into several parts, some of them
were like being atomized  to dust...

Is anybody out there having a good idea what happened to the
ceramics?
The crucibles were new, clean ones and had been baked out several
times prior to using them, the temperature of the oven was adjusted to
1200C, it showed being 1175C. We did not open the oven until the
temperature was down.

I have no idea what we didn't do right if we did something wrong (which
to a certain extent I expect, as Irene, you give this method as your
routine one)

Hope somebody could help.

Anette

Datum:          Wed, 29 Jun 2005 18:52:14 -0400
Antwort an:             Stable Isotope Geochemistry <[log in to unmask]>
Von:                    Irene Ellis <[log in to unmask]>
Betreff:                Re: [ISOGEOCHEM] Ion Source Cleaning
An:                     [log in to unmask]

Cleaning an ion source with solvents will leave a thin film of the
azeotrope unless precautions are taken.

This is the sequence that I used for the metal parts:

--non-ionic soap and water after polishing off all carbon and sonicate 15
min.

--deionized water 3X and sonicate each time

--methanol to cover, sonicate, decant and drain as much as possible by
capillary action to kimwipes (metal parts stay in beaker, drain at lip)

--chloroform to cover, sonicate, and decant.  Bake dry at 80C (about an
hour).  The beakers can then be sealed with new Al foil.  Store in
dessicator if waiting longer than overnight.

This leaves all parts clean and the source will not need to bake out longer
than the time to pump down.

To clean ceramics, put into clean crucible and bake overnight at 1200C.  No
need to scrape or sandblast--the carbon just evaporates perfectly. NB you
will destroy MACOR insulators this way if any such nasties are lurking in
the same lab (personal pet peeve).

Irene Ellis
IsoTrace Lab, U of T----------------------------------------------------------------------
Dr. Anette Giesemann
Institute of Agroecology, Federal Agricultural Research Centre
Bundesallee 50, D-38116 Braunschweig
Tel.:++49 531/596-2538; FAX: ++49 531/596-2599
E-mail: [log in to unmask]

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