Dear Georges,

I would definitely use Tim's advice.
I have been working on atmopsheric and road traffic particles for a couple of years on different isotope systematics (C, N...) using QM-A (Whatmann or Schleicher & Schuell) on our EA and never got any problem.

To clean the furnace, I made up a vaccum system connected to our lab's hoover.

David

Dr D. Widory
BRGM MMA/ISO
3 avenue Claude Guillemin
BP 36009
45060 Orléans Cedex 2
France
e-mail : [log in to unmask]
Tel. : (0)2 38 64 47 72
Fax : (0)2 38 64 37 11
  

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Georges Paradis
Sent: 03 July 2008 18:56
To: [log in to unmask]
Subject: [ISOGEOCHEM] Sulfur on filters

Hello Everybody,

I'm having a terrible time with d34S analysis of particulates on glass 
fiber filters using a Delta Advantage/Costech 4010 EA.   The filters 
were prepared in tin caps using 1mg V2O5 catalyst. The SO2 peak shape and sensitivity deteriorate after running just a few filters. I've tried altering the O2 amount, the sample delay timing, and replacing the water trap. The only way to regain good peak shape and sensitivity (complete
combustion) is to replace the ash liner.  There seems to be something in the filter media or the particulates on the filter that are affecting combustion and chromatography. 

The exact same sample prep and analytical conditions are working well for 4 mg marine invertebrate tissue samples. The problem is only with the filter samples.

Any clues or suggestions would be greatly appreciated.

Thank you,
Georges

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Georges L. Paradis
Analytical Lab Manager
Marine Science Institute
Bldg 520, Room 4013
University of California Santa Barbara
Santa Barbara, CA 93106
805-893-7182 (ICPMS lab)
805-893-3802 (MSI lab)
[log in to unmask]
http://analab.msi.ucsb.edu/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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