Principle of method validation

When is method validation necessary?

Every newly developed method must be validated prior to sample analysis. Validation must also be repeated if a parameter has been modified or if the validation was originally performed in another laboratory, to ensure that the methods are transferrable. A verification is necessary if the analyst or instrument have been changed, or if the sample type has been modified.

How to validate a method?

The analyst should consider the customer requirements, plan and perform the suitable experiments to validate the method, taking into account matrix, analyte properties and concentration, purpose of the analysis etc. The data obtained must be fit for the customer�s purpose or, if it is not, its limitations must be stated. Some of the parameters studied include:

  � Accuracy
  � Precision
     Repeatability
     Reproducibility
  � Robustness
  � Range

Standards, reference materials, blanks, spikes, statistics etc. are commonly used tools during the validation process.