Q: Klett-Unit???

Paul N Hengen pnh at cockleberry.ncifcrf.gov
Sat Nov 18 20:37:11 EST 1995


Rafael Maldonado (rafael at howard.genetics.utah.edu) wrote:

: The complete name is Klett-Summerson photoelectric colorimeter. It is an 
: old fashioned spectophotometer. To mesure OD in a given wavelength, a 
: filter should be used. So mesurements in Klett units should include the 
: filter used, as we do with the OD in a spec: OD600 nm, or filter D30 of 
: the Klett colorimeter. Since the colorimeter includes two filters, D10 ( 
: 420 nm) and D35 (540 nm), the mesurements of cultures were made at 540 
: nm, more or less...

: the OD unit as arbitrary as Klett units, and OD units are only reliable 
: in your own machine and on your own strain, after counting how many cells 
: correspond to OD in your machine.

: By the way, those flasks which Hiranya talked about are really useful. 
: You can measure the turbidity without open the flask; of course, you 
: could use some tubes for mesuring, as we use cuvettes in modern spec.

I've used a Klett for determining the viable cell number vs. Klett unit for E.
coli when making competent cells for transformation. If that is your purpose,
I can provide you with the growth curve. BTW, the flasks are called "Nephelo"
flasks which can be bought from Bellco. They are great for making competent
cells because you don't risk contamination.

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