Why should I fill the cuvette at least half full and check for air bubbles?
If you do not place enough sample in the cuvette, the light beam will pass through air instead of your sample solution.
Here are two meter readings of the same sample...
...when the cuvette is 1/4 full(!)
...and when it's approximately 3/4 full
Air bubbles in a cuvette can also cause the same effect to a lesser degree.
Bubbles may indicate that your cuvette is dirty!
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