Some photometers use a reference cuvette in addition to the sample cuvette.
Problems with cuvettes may include:
(1) fingerprints or smudges on the outside of the cuvette (may absorb key wavelengths)
(2) dried solutions or other debris on the outside of the cuvette
(3) failure to match the test cuvette with the reference cuvette (using different cuvettes)
(4) cracked or broken cuvette
(5) improperly seating the cuvette into its holder
(6) misalignment of one or both cuvettes to the light source
(7) air bubbles, contaminant or debris in one or both cuvettes
(8) using the wrong cuvette
(9) using a cheap cuvette made of the wrong material
(10) incomplete filling of the cuvette
(11) failure to mix solutions completely before filling the cuvette
