What orientation is correct when inserting cuvettes into a spectrophotometer?

What orientation is correct when inserting cuvettes into a spectrophotometer?

• A. Cuvettes should be inserted with the clear side facing the light
• B. Cuvettes should be inserted with the colored side facing the light
• C. Orientation does not matter
• D. Cuvettes should be removed during measurement

Answer: (A)

Light must pass through an optically clear window of the cuvette to accurately measure how much light the sample absorbs. Placing the clear side toward the light path minimizes additional absorption or scattering from the cuvette walls, so the reading reflects only the sample’s properties. The opposite side is often tinted or frosted and can contribute extra attenuation, leading to an erroneous result. Keep the cuvette clean and handle it by the edges so fingerprints don’t interfere with the clear window. Consistency in orientation ensures repeatable measurements across samples.

Light must pass through an optically clear window of the cuvette to accurately measure how much light the sample absorbs. Placing the clear side toward the light path minimizes additional absorption or scattering from the cuvette walls, so the reading reflects only the sample’s properties. The opposite side is often tinted or frosted and can contribute extra attenuation, leading to an erroneous result. Keep the cuvette clean and handle it by the edges so fingerprints don’t interfere with the clear window. Consistency in orientation ensures repeatable measurements across samples.