Dr. Rafael N.G.,

Sometimes, solvent cleaning with sonication gives a significant decrease in
background carbon from the tin samples holders, othertimes not. It seems best to
check each new lot of holders to make sure they are not badly contaminated.
       
It is fairly routine procedure here to solvent clean the tin sample holders
using sonication. The sample holders are then carefully handled to avoid solvent
residue contamination, or contamination after drying or during storage.
This unfortunately will not do anything for the carbon in the metal matrix.

Glen Martin

 02:05 PM 5/27/98 +0200, you wrote:
>Dear all working with EA-IRMS (better if NA1500)
>
>Currently I am trying measuring samples with quite low amount of carbon. In
>order to get a normal signal in my mass, I have increased my emission
>current (of course, working in a range where I am able to weigh the
>samples). But now I have increased my blank signals as well!. My empty tin
>capsules give me now around 7% of the signal in a normal sample. I think
>washing with a organic solvent could reduce this blank, Which would you
>recomend me? or is it possible to buy better tin capsules?
>Regards
>Rafael
>Dr. Rafael Nuñez Gomez
>Dpto. Ciencias de la Tierra y Quimica Ambiental
>Estacion Experimental del Zaidin
>Consejo Superior de Investigaciones Cientificas
>Profesor Albareda 1, 18008 Granada, Spain
>Tf 34-958-121011 Fax 34-958-129600
>email: [log in to unmask]
>http://www.eez.csic.es/~isotopos
>
>