Which item in the clinical laboratory does not require calibration?

• A. Electronic balance
• B. Liquid in glass thermometer
• C. Centrifuge
• D. Volumetric flask

Answer: (D)

Calibration in the clinical lab is about ensuring measurement accuracy for devices and glassware. An electronic balance must be calibrated with standard weights to account for drift and environmental factors, so its mass readings stay true. A liquid-in-glass thermometer needs calibration against fixed temperature points to ensure the reading reflects the actual temperature. A centrifuge requires calibration for speed and timing to guarantee consistent force and separation. In contrast, a volumetric flask is manufactured to deliver a precise volume when filled to its marked line, with that accuracy specified by the glassware’s certification. When used properly, it provides a known volume without needing routine recalibration, making it the best choice.