When should Calibration Verification be performed during an analysis day?

• A. Beginning and end of each analysis day.
• B. Only at the start.
• C. Only after every twenty samples.
• D. Only when calibration fails.

Answer: (A)

Calibration Verification is about confirming the instrument stays within specification so that results are reliable throughout testing. Doing it at the start of the analysis day ensures you begin with an instrument that is in tolerance, reducing the risk of biased or invalid results from the first run. Rechecking at the end of the day verifies that the instrument remained stable over the whole set of analyses, catching any drift or changes that occurred during the day and preventing unrecognized inaccuracies from being reported as final data.

If CV were performed only at the start, drift during the day could go unnoticed. If it were done only after a fixed number of samples, there’s still a risk of accumulating undetected drift between checks. Waiting until a calibration fails is too late for data integrity, as results may already have been produced and used. Therefore, performing Calibration Verification at both the beginning and the end of each analysis day best protects accuracy and traceability.