IUBio

Disposable spectrophotmetric cuvettes

Shiao Wang Shiao.Wang at usm.edu
Fri Mar 12 14:14:58 EST 1999


> every time you handle a quartz cuvette you run the risk of breaking the damn
> things:  "Oops...tinkle...there goes another 250 bucks!" The Fisher ones were
> the smallest I could find too, and they say the min volume is 1.2mL...

Using the same cuvette, the minimum sample volume required for an
accurate reading depends on the spectrophometer. If you have not done so
already, you should determine the minimum volume requred in your
spectrophotometer.

1. Adjust the height of the cuvette so there is no wasted sample below
the light beam. Some cuvette holders have a set screw at the bottom for
height adjustment. Alternatively, place some solid object under the
cuvette to raise it. Set the spectrophotomer for % transmittance, blank
and then gradually adjust (raise) the height of the cuvette until %
transmittance is affected. Back it down slightly and that's your
optimized cuvette height.

2. Starting with an empty cuvette, add 100 ul sample and take an
absorbance reading. Repeat with additions of 100 ul sample until the
reading becomes consistent. The volume required for a consistent
measurement is your minimum volume. You can fine tune with smaller
volume increments.

Good luck and best regards.

-- 
Shiao Y. Wang
Department of Biological Sciences
University of Southern Mississippi



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