The following statement about XRF calibration checks is true: ‘A calibration check should be performed before an inspection begins; after the inspection is completed, or at least every 24 hours, whichever occurs first’

• A. True
• B. False
• C. Not Applicable
• D. Not Stated

Answer: (B)

Calibration checks are a QA step used to confirm the XRF instrument is giving accurate readings before and during use. The statement as written implies you only need a check before starting, then either after finishing or once every 24 hours, whichever comes first. That schedule is not how the checks are typically treated in practice. Drift and changes in temperature, sample type, or instrument conditions can affect results fairly quickly, so checks are performed not just at the start and end or once daily, but at regular intervals during use and after any event that could affect accuracy. Because relying on a single check at the start and then waiting up to 24 hours can let drift go undetected, the described requirement isn’t correct. In reality, you calibrate before the inspection and then at appropriate, shorter intervals during use (and after events that could affect performance), ensuring readings stay within acceptable tolerance.