What is method validation and how to do it
This document is intended to provide a basis for a common understanding of the activities related to validation of test methods.
Validation is defined as confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use are fulfilled.
In the validation process, the objective is to estimate the representativeness, repeatability and reproducibility of the test method and secure adequate evidence that the method is its intended purpose.
The laboratory have to use appropriate methods and procedures for all tests/or calibrations within its scope. These includes sampling, handling, transport, storage of items to be tested and calibrated, and where appropriate , an estimation of the measurement uncertainty as well as statistical techniques for analysis of test and/or calibration data.
Standardized test methods published by National and International standards bodies ( IS/ISO/IEC) or independent technical bodies ( ASTM,AOAC,IAEA etc.) or regulatory bodies ( Indian Phamaeopoea, EPA etc.) should be considered validated for their intended application ( range and accuracy of measurement) and thus fit for the intended purpose, even if the repeatability and reproducibility are not known in detail. The testing laboratory must ensure that they apply the method correctly.
For modified test methods or in-house developed test methods the testing laboratory should determine the level of repeatability and reproducibility, keeping in view , the factors which affect the test results are sampling , homogeneity , test method , equipment , personnel and test environment.
The effect of instrumental and technical factors can be minimized and controlled by making provisions like defining the equipment capability (range & accuracy) as precisely as necessary , providing a clear description of the test procedure including instrument operation and establishing procedures for operational control and calibration of equipment with traceability of measurement .
Clause 5.4.5 VALIDATION OF METHODS
Human factors are controlled through education/basic knowledge, practical experience and on job training.
The Qualification required for the personnel employed for a given test may, if necessary, be specified in the test method or in internal procedures. Environmental factors where they affect the test results are controlled and parameters are atmospheric conditions like temperature, pressure and humidity, contamination and other factors like EMC. The effect of any of the above factors on the test result shall be described in the test methods.
C0-operation between a certain numbers of laboratories working in the same area for inter-laboratory comparisons provides the desired confidence particularly in case of modified test method and is recommended.
The validation of test methods shall satisfy two inter-related steps are suitability of the test to satisfy the customer needs, and the demonstration of technical capability of the test method within the specified range.
