ABSTRACT
Method validation is the process to confirm that the analytical procedure employed for a specific test is suitable for its intended use. Methods need to be validated or revalidated as follows:
Before their introduction into routine use Whenever the conditions change for which the method has been validated
(e.g., instrument with different characteristics) Whenever the method is changed, and the change is outside the original
scope of the method When quality control indicates an established method is changing with
time In order to demonstrate the equivalence between two methods (e.g., a new
method and a standard) Method validation has received considerable attention in the literature and from industrial committees and regulatory agencies. The international standard ISO/ IEC [1] requires validation of nonstandard methods, laboratory designed/developed methods, standard methods used outside their intended scope, and amplifications and modifications of standard methods to confirm that the methods are suitable for their intended use. The Guidance on the Interpretation of the EN 45000 Series of Standards and ISO/IEC Guide 25 includes a chapter on the validation of methods [2] with a list of nine validation parameters. The International Conference on Harmonization (ICH) of Technical Requirements for the
Registration of Pharmaceuticals for Human Use [3] has developed a consensus text on the validation of analytical procedures. The document includes definitions for eight validation characteristics. An extension with more detailed methodology is in preparation and nearly completed [4]. The U.S. Environmental Protection Agency (U.S. EPA) prepared a guidance for methods development and validation for the Resource Conservation and Recovery Act (RCRA) [5]. The American Association of Official Analytical Chemists (AOAC), the U.S. Environmental Protection Agency (EPA), and other scientific organizations provide methods that are validated through multilaboratory studies.
