What is the difference between a Calibration and a Performance Verification?

Calibration is a process where an instrument is set to provide a “correct” response to a given set of conditions. E.g. A time piece is calibrated by setting the hands to the correct time, a balance is calibrated by adjusting it so that it correctly displays a given weight etc.

A Calibration is carried out by challenging an instrument with known standards and adjusting its responses until it reliably provides the correct answers within acceptable tolerances. Once an instrument has been calibrated, it will drift after a period of time which will depend on the operating principle and robustness of the instrument.

Performance Verification
The data provided by some instruments is based on First Principles of Physics which means that, provided the instrument has been correctly constructed and is used correctly, the data will always be within pre-defined limits which will not be subject to drift.

Such instruments include Malvern’s laser diffraction-based particle size analysers and our Zetasizer Nano Series of instruments.

The Performance Verification process for such instruments is one of challenging the performance of the instruments by measuring known standards. The accuracy of this process relies on the traceability and reproducibility of the standards used and the reliability of the standard measurement procedures used. In the event that the results of the Performance Verification process fall outside established pass/fail criteria, the correction process is one of checking the integrity of the fundamental setup of the instrument rather than adjusting potentiometers, sliders, spring tensions, gaps or torques.

Why verify performance?
Although instruments based on first principles do not need to be calibrated, users still need to be regularly assured of their continued integrity.

In many cases, particularly in the pharmaceutical industry, where an instrument determines the safety or acceptability of a prescription drug, regular Performance Verification is an essential part of the Validation process ensuring that the product’s efficacy and safety continues to meet the rigorous standards agreed with Clinical and Regulatory Authorities.