Dear Klaus,
can you recommend any quartz filters that worked well for your applications?
Did you modify precleaning of those filters as compared to GF/F?
Thanks for your hints
Klaus



----------------------------------------------------------------
  Klaus Dittert, PhD.
  Institute of Plant Nutrition and Soil Science
  Kiel University
  Olshausenstrasse 40-60
  D-24118 Kiel, Germany
  phone + 49 431 880 3196
  fax + 49 431 880 1625
  email: [log in to unmask]


----- Original Message -----
From: Klaus-Uwe Richter <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, February 15, 2000 9:21 AM
Subject: Re: quartz fiber filters


> Dear Paul,
>
> we compared glasfiber filters with quartz fiber filers for field sampling
> of marine plankton and found no significant differences in the isotopic
> composition for 13C and 15N. We used quartz fiber instead of glas fiber
out
> of the same practical reasons you mentioned. The only disadvantages of
> using quartz fiber are:
> 1: the reduced capacity of our ANCA system because the volume of quartz
> fiber stay nearly the same before and after oxidation, filling up the
> oxidation tube quickly
> 2: difficulties to to press the quartz filters in tin vials to get them
> into a spherical shape for the autosampler (we normaly use a special hand
> press for filter samples)
> 3: differences in poresizes between commericial available quartz and glas
> filters (classical definition of dissolved versus particulate matter in
> marine POM studies)
> 4: we had higher blank values for quartz fiber filters during the acid
> fuming step, most probable reason is the higher amount of fiber in the
> thick quartz fiber filters we used in comparison to the normal thin
GF/F´s.
>
> Altogether we are quit happy with the quartz fiber filters since
> (1) evenso we have to clean the oxidation tube more often this job is much
> more easy with quartz fiber/ash than with molten glas and the tube it is
no
> longer damaged by molten glas sticking to the inner walls and metal oxide
> packing of the tube
> (2) with some tryouts it was possible to find a suitable folding technique
> for the tin foil
> (3) depending on the application different poresize can often be used
> without a problem
> (4) blanks were only a problem at very smal sample sizes
>
> I hope this helps,
>
> Klaus-Uwe Richter
>
> Alfred-Wegener-Institut fuer Polar- und Meeresforschung
> Am Handelshafen 12
> 27570 Bremerhaven, GERMANY
> Tel: 0471 48311482
> Fax: 0471 48311425
>