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Stable Isotope Geochemistry

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Subject:
From:
John Hill <[log in to unmask]>
Reply To:
Stable Isotope Geochemistry <[log in to unmask]>
Date:
Tue, 20 Jan 2009 16:22:01 +0000
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Istvan

Have you changed all the source ceramic insulators?
It only takes one insulator that is contaminated or cracked to cause 
leakage and hence create focus or deflection problems.
We have to change all the ceramics on organic instruments every time as 
they soon get dirty and cause all sorts of problems.

Regards

John Hill
Mass Spectrometry Facility
Chemistry Dept.
University College London
20 Gordon St.
London
WC1H 0AJ

Tel: +44 (0)20 7679 4605
Fax: +44 (0)20 7679 7451


Fórizs István wrote:
> Dear Andrew,
> 
> thank you very much for your advice. I have checked the possible 90 
> degree off, but this is not the case.
> The problem must be something else. I will let you know - hopefully soon 
> - what the problem is.
> 
> Best wishes
> Istvan
> 
> Andrew Schauer írta:
>> With your 18 years, I hardly feel qualified to say anything at 
>> all...but I recently observed the very same thing on our DeltaPlus 
>> (Advantage) with my significantly less than 18 yrs experience 
>> (p<0.05). My problem was putting the source together 90 degrees off 
>> from correct. The ceramic posts make a square, and thus, it possible 
>> to put it together 90 degrees off. My signal was about 10% of normal 
>> and focusing was, of course, way off. I would be interested in hearing 
>> the fix.
>>
>> andy
>>
>>  Andrew Schauer
>> ISOLAB
>> Department of Earth and Space Sciences
>> University of Washington
>> Seattle, WA 98195
>>
>>
>> 206.543.6327
>> [log in to unmask]
>>
>>
>>
>> ----- Original Message ----
>> From: Fórizs István <[log in to unmask]>
>> To: [log in to unmask]
>> Sent: Monday, January 19, 2009 8:23:48 AM
>> Subject: [ISOGEOCHEM] ion-source
>>
>> Dear Colleagues,
>>
>> I have been mainatining stable isotope ratio mass spectrometers for 18 
>> years. Usually I do the ion source cleaning, and untill now there have 
>> been no problem with it.
>> Recently (first week of January) together with one of my colleagues we 
>> cleaned the ion source of our Finnigan delta plus XP.
>> After the maintainance we noticed that the height of the peak of the 
>> reference gas CO2 is about half of that it was before the celaning. 
>> The same is true for the H2 reference gas. At the same time the 
>> focusing does work well. E.g. the Y Deflection 1 and 2 was around 40%, 
>> BUT now Y Deflection 1 is at 100%, and Y deflection 2 is 96%.
>> We tried to do measurements, but we got strage values.
>>
>> I think that when we assembled the ion source, we did something wrong. 
>> Therefore we took off the ion source, disassembled it, but we did not 
>> notice any unusual. We assembled again the ion source and the result 
>> is the same. Half peak and bad "focussing" values.
>>
>> I would appreciate very much if somebody can tell us good hints on 
>> what we did incorrectly.
>>
>> Best regards
>> Istvan
>>
>> -- 
>> -------------------------------------------------------------------------
>> Dr. FÓRIZS István  ..........  Istvan FORIZS Ph.D.
>> Magyar Tudományos Akadémia Geokémiai Kutatóintézet
>> Institute for Geochemical Research, Hungarian Academy of Sciences
>> Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
>> Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
>> Fax: (36-1)-319-3137
>> Http://www.geokemia.hu/people/forizs_hu.html
>> -------------------------------------------------------------------------
>>
>>
>>
>>   
> 

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