 
Tue, 26 Jul 2005 18:05:39 +0800
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HiJohn,
we had just this problem last year, at last this was solved only by
baking for more time. Maybe you can try, baking continually the
capillaries,every time less than 10 minutes.
cheers
zengjie
***********************************************
Zengjie Zhang
Assistant Professor
The Open Research laboratory on Isotope Geology
Chinese Academy of Geological Sciences
26 Baiwanzhuang Road, Beijing
100037, China
86-10-68999635(lab) 86-10-68999094(O)
[log in to unmask]
Question Is Everything
<br><br><br>>From: J T Hill <[log in to unmask]><br>>Reply-To:
Stable Isotope Geochemistry <[log in to unmask]><br>>To:
[log in to unmask]<br>>Subject: [ISOGEOCHEM] Contamination on
253<br>>Date: Mon, 25 Jul 2005 16:51:16 +0100<br>><br>>Hiya
All<br>><br>>Does anyone have experience of cleaning the capillaries
and <br>>change-over<br>>valve on a 253/Kiel?<br>>We think we have
a contamination problem as the internal precision <br>>and<br>>delta
value are OK for a time then there are "bursts" in which the
<br>>value is<br>>erroneous by up to almost 1 per mille each way.
This is for carbon <br>>or<br>>oxygen and sometimes both. We think
the instrument itself is OK as <br>>the<br>>system stability tests
check out. The problem may be due to <br>>phosphoric acid<br>>finding
its way into the capillaries and or contamination from bulk
<br>>samples<br>>from the Kiel. Baking these parts for a few hours
has made no <br>>difference.<br>>If contamination is the cause, we
shall have to clean the <br>>capillaries and<br>>changeover block and
valves. We can probably arrange an HPLC pump to <br>>pump<br>>liquid
through the capillaries and we have ultrasonic baths. The
<br>>expense<br>>of simply replacing all these parts is so great that
we would prefer <br>>to<br>>decontaminate the existing parts if
possible.<br>><br>>Regards<br>><br>>John<br>><br>><br>><br>>John
Hill<br>>Mass Spectrometry Facility<br>>University College
London<br>>Chemistry Department<br>>20 Gordon
St.<br>>London<br>>WC1H 0AJ<br>><br>>Tel: 020 7679
4605<br>>Fax: 020 7679 7451<br>>Mobile: 07956 924058<br>
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