Which cleaning practice should be avoided when preparing cuvettes for measurement?

• A. Use a Brush to Clean the Insides of the Cuvette
• B. Fill the Cuvette About 3/4 Full of Test Solution
• C. Wipe the Outside of the Cuvette with a lint-free Tissue
• D. Do Not Scrub the Insides with a Brush

Answer: (D)

Keeping the interior of cuvettes free from scratches and residues is essential for accurate optical measurements. Scrubbing the inside with a brush is not advisable because the bristles can scratch the inner surface and shed fibers or debris. Scratches and fibers scatter or absorb light differently, skewing the measurement and compromising the data. The preferred approach is to avoid abrasive cleaning and instead rinse or flush the interior with deionized water or an appropriate solvent using gentle, non-abrasive methods, then dry with a lint-free tissue or allow to air-dry. Wiping the outside with a lint-free tissue is fine for removing fingerprints, but interior scrubbing should be avoided. Filling the cuvette to a certain level is about sample preparation, not cleaning.