Paul,
           We have not tried quartz filters but find that the quartz
basket liners which fit inside the oxidation tube are fine for
containing the remains of GF filters so that they don't stick to the
actual furnace tube or it's packing (or block the furnace). The whole
liner can be removed and it is often possible to extract the fused
glass remains from the liner and re-use it.
   We have also experimented with ceramic (alumina) membrane filters
for plankton etc. After catching the sample on them they are dried and
the outer support ring removed. They can then be ground up, sample and
all, between two watch glasses or in a mortar and pestle and placed
into tin cups as any normal ground sample.  Their main disadvantage is
that they block up after filtering only a few ml of water if it is
even remotely turgid. We also never managed to completely eliminate
the carbon blank from the filter itself, they cannot be ashed before
use as the support ring will not tolerate the necessary temperatures.


                                                            Darren.



Darren Sleep
Stable Isotope Facility
ITE Merlewood
Grange-Over-Sands
Cumbria LA11 6JU
UK