Key Topics

Introduction to method validation

Method validation is defined in the standard ISO/IEC 17025 as, “The confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled.” Method validation therefore provides documented objective evidence that a test method measures what it is intended to measure, with an acceptable level of performance.

The ISO/IEC 17025 definition has three important parts which help to outline the validation process:

• ‘specific intended use’: Measurements are made to help answer a specific question or solve a particular problem. To enable a suitable test method to be selected, the analyst needs to understand why the samples are being analysed and what the resulting data will be used for.
• ‘objective evidence’: This is the set of results generated from planned experimental studies which are going to be used to evaluate the performance of the chosen test method.
• ‘confirmation’: This is the final step of the validation process. Information on method performance, obtained from the experimental studies, is compared with the performance that is required to meet the customer’s requirements. If the comparison demonstrates that the method performance is satisfactory, then the method is declared fit for purpose and the validation process is complete. If the performance is unsatisfactory then further refinement/development of the method is required.

Method validation is an essential part of good measurement practice because valid data can only be produced when the strengths and weaknesses of the test method are understood.