Fellow analysts:

We have worked around but been somewhat frustrated in the past with the
build up of glass in the EA furnace when analyzing 15N-NH4 diffused onto
GF/F filter papers.  I seem to recall someone had used quartz fiber filters
instead, but couldn't find a definite reference to this.  I note that
quartz fiber filters are
available
(http://www.coleparmer.com/catalog/product_view.asp?referred_id=778&sku=2970610).


  Has anyone tried NH4 or NO3 diffusion with quartz fiber filters, and then
run them on an EA-IRMS?

Thanks in advance,

Paul Brooks.