From: Holger Strauss <strauss@fmp-berlin.de>
  To  : Joel Mackay <j.mackay@biochem.usyd.edu.au>
  Date: Mon, 26 Mar 2001 12:52:18 +0100 (MET)

Re: repairing/replacing centrepieces

Hi Joel,

from my experience it is a good idea to talk to the person doing the
glass-work at your institute or to an optician to repolish the
centerpieces. Usually these people can do miracles to old and worn
centerpieces (we had the problem with plenty of material left from the
Model E). It's best to use some natural abrasive, since the edges of those
particles are more rounded than those of artificial ones, which are
obtained from a grinding process. You will loose some micrometers off the
optical pathlength, however, for 1.2 cm centerpieces, that is not too much
and in most cases works fine, for 3 mm centerpieces that might be a
fact that has to be taken into account. It is possible that the sides
of the centerpiece won't be exactly
parallel after the polishing, but you can remedy that by using two
instead of just one window gaskets, which will give more tolerance to the
window and hence improve the seal. The mistake in
concentration determination should be within the noise of the instrument,
at least for the absorbance optics and 1.2 cm centerpieces.

Holger

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Holger Strauss 

Forschungsinstitut fuer Molekulare Pharmakologie (FMP)
Robert-Roessle Strasse 10

13125 Berlin/Germany

Tel: +49 (0)30 94793 - 223 (office)
                     - 316 (lab)

Fax: +49 (0)30 94793 - 169 


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