Which practice is most characteristic of quality control in the laboratory?

• A. Running control samples with each batch to monitor performance
• B. Validating a new method before use
• C. Lab safety training
• D. Standard operating procedures

Answer: (C)

Quality control in the lab focuses on the ongoing assessment of the analytical process to ensure accurate and precise results. The most characteristic practice is running control samples with each batch to monitor performance. These controls have known values and are treated like patient samples, allowing you to detect calibration drift, reagent issues, instrument problems, or other shifts in the process. When control results stay within predefined limits, you gain confidence that the batch results are trustworthy; if they go out of range, you stop reporting patient results and investigate the cause.

The other options relate to different parts of quality and safety systems: validating a new method before use is about establishing a method’s reliability before routine testing; lab safety training centers on protecting personnel and ensuring safe operations; standard operating procedures provide the framework for consistent methods but are not the ongoing performance check itself.