We have a Europa 20-20 coupled to a Roboprep C/N analyser and use the quartz
liners routinely. In answer to your questions:

1) We do NOT place any Chromium Oxide into the liner, but it is important to
make sure you fill the oxidation tube to the correct height. With the old
system using nickel sheets an extra 10mm CrO3 was placed into the Ni sheet
as I recall . You must add this 10mm to the CrO3 already in the tube before
you place the liner on top. You also need to place a small plug of quartz
wool at the bottom to seal the liner otherwise the ash falls out when you
lift it out of the oxidation tube.

2) We clean the liners by poking out the ash with a metal rod and scrubbing
the inside with a test tube brush. It is important to clean the slits in the
sides well and make sure the holes are free of ash. This allows O2 and
carrier to flow freely around the samples when they drop. I find the best
tool for this job is a finger nail! After scrubbing we rinse in alcohol and
finally in deionised water before drying well in an oven.

3) As for replacement, it depends on sample type. For Plant material with
typical sample sizes of 4-6mg I find that about 200 is the max amount of
samples you can run before you need to change the liner. With soils or
diffusion discs however I change the liner after each batch routinely.
(50-60 samples) as they are so big.

Hope this helps

Jon Fear....

Senior Laboratory Technician
Department of Agricultural Sciences
Imperial College at Wye
Wye
Ashford
Kent TN25 5AH.

Tel:020 759 42879
Fax: 020 759 42640
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