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Selecting Ultra-Micro Cuvettes for
Your Spectrophotometer
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For detection,
spectrophotometers shine a beam of light through a sample in a cuvette. The
height of the beam from the bottom of the cuvette chamber is termed the “beam
height.” Two competing industry “standards” have developed for the beam height:
8.5mm and 15mm.
When working with macro and semimicro cuvettes, the beam height determines only
the minimum fill volume; the cuvette must be filled enough to reach the spectrophotometer
beam height. In contrast, the volume of sample in an ultra-micro cuvette is
so small that the sample chamber in the cuvette must be elevated from the bottom
of the cuvette so that the sample lines up with the light beam.
Because of the competing standards for spectrophotometers, ultra-micro cuvettes
are made with window heights that align with either the 8.5mm or 15mm beam-heights.
It is critical that the window height of your ultra-micro cuvette matches the
beam height of your spectrophotometer. With the wrong window height, the beam
either will not pass through the sample at all, or will need much more than
the minimum-specified sample volume to provide a result.
Before selecting an ultra-micro cuvette, you need to know the beam height of
your spectrophotometer. If you aren’t certain of the beam height of your spectrophotometer,
check the list below. If your spectrophotometer is not listed, consult the operating
manual of your instrument.
Note: Data in this application were collected from public sources, and are correct to the best of our knowledge at
the time of publication. This is provided as a customer convenience. Manufacturers may choose to offer instruments
conforming to either standard for technical or corporate reasons. BrandTech Scientific does not manufacture
spectrophotometers, and makes no warranty regarding the information provided by this application.
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