R. I. Mateles rmateles at candida.com
Thu Jun 24 16:12:32 EST 1999

Klett's are old, but they are (were) quite useful.  They do not function at
a narrow wavelength, but they give perfectly valid curves of reading vs. dry
weight after you calibrate them for the particular suspension you are
measuring.  If you use a spectrophotometer, you still need to prepare a dry
weight vs. OD curve for each type of suspension, it's all more "modern", but
the results are about as good or bad as with a Klett!  In both cases you get
a mixture of scattering and absorption. and in both cases you have a more or
less linear part of the curve and a part which is non-linear (at higher

Rich Mateles


Candida Corporation
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rmateles at candida.com
<ash at umich.edu> wrote in message
news:x5vc3.127$q95.3937 at news.itd.umich.edu...
> Can somebody tell me a little bit about Klett meters and how they
> may differ from a spectrophotometers?  The ones I have seen were
> stout hot little gray metal boxes using filters and seemed
> to be nothing more than a light source, a slit, a sample chamber and
> photomultiplier tube.  Why do researchers still use these antiques?
> Most importantly I would like to know what sort of units are
> the Klett units.  How can I interconvert Klett units to Abs600nm or
> Abs550nm units without actually sitting down and doing the experiment
> with my nonexistent Klett and my trusty Milton Roy 1001 Spectronic+?
> Particularly I am thinking of measuring the absorbances of
> bacterial suspensions.  That is not technically the absorbance of Beer's
> Law, but rather a mixture of absorption and scattering in a
> colloidal suspension.  Any discussion would help.
> Andrew Heath <ash at umich.edu>

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