Many important decisions are made on the basis of analytical results. Getting the right result is therefore essential. Laboratories use a variety of approaches to help ensure that they get the right result. One of these is method validation.

Users of the analytical results may therefore require that a laboratory uses validated methods - either asking for this directly or by requiring the laboratory to be accredited against a standard which requires method validation. So, what exactly is validation and what types of validation are available to laboratory managers?

Validation is confirmation that the method meets the requirements for a specific intended use - that is, that the method is fit for purpose.

This document focuses on method validation - demonstration that the method is fit for purpose when performed correctly. Many "standard" methods have already been validated and the laboratory may not need to do further method validation, only laboratory assessment – that is, demonstration that a laboratory performs a method correctly. Laboratory assessment is a much wider issue, which would take in aspects such as accreditation (i.e. formal recognition that laboratory or person is competent to carry out specific tasks) and proficiency testing (inter-laboratory trials through which laboratories can judge their performance) – and is beyond the scope of this short paper.

Method validation inevitably involves some specific, technical language (i.e. jargon) and statistics. There is therefore a glossary at the end of this document.

Types of method validation procedures

There are confusingly many ‘standard’ procedures indicating how methods should be validated. Two very influential organizations, each publishing a range of procedures, are:

• ISO - a worldwide federation of national standards bodies.
• AOAC - a globally recognized, independent, third party, not-for-profit association and voluntary ‘consensus standards’ developing organization.

Procedures differ in many ways including:

Scope:

• Method type: quantitative or qualitative analytical methods
• Analysis type: such as chemistry, microbiology, drug development, and agriculture
• Material: water, foods

Procedure characteristics

• Number of laboratories involved
• Characteristics assessed; e.g. precision, trueness or bias

To help you choose an appropriate procedure, or anticipate which procedures you might be expected to follow, this document briefly describes some procedures published by some of the authoritative bodies. The descriptions are not intended to be complete – you will still need to read the actual procedures. Also, the list is not exhaustive – there are many procedures not covered here. Nevertheless, this document should help you avoid having to consult many procedures which are not appropriate to your circumstances.