The terms method validation and method verification are often used interchangeably, but they represent two distinct processes in the laboratory. Understanding the difference is crucial for ensuring your laboratory is compliant with ISO/IEC 17025.

Method Validation

Method validation is the process of confirming that a method is fit for its intended use. It is required for:

  • Non-standard methods
  • Laboratory-developed methods
  • Standard methods used outside their intended scope
  • Validated methods that have been modified

Validation is an extensive process that involves establishing a range of performance characteristics, such as:

  • Accuracy: The closeness of agreement between a test result and the accepted reference value.
  • Precision: The closeness of agreement between independent test results obtained under stipulated conditions. This includes repeatability and reproducibility.
  • Linearity: The ability of the method to produce results that are directly proportional to the concentration of the analyte in the sample.
  • Limit of Detection (LOD): The lowest amount of analyte in a sample that can be detected but not necessarily quantitated as an exact value.
  • Limit of Quantitation (LOQ): The lowest amount of analyte in a sample which can be quantitatively determined with suitable precision and accuracy.
  • Robustness: A measure of the method's capacity to remain unaffected by small, but deliberate variations in method parameters.

Method Verification

Method verification is the confirmation that the laboratory can properly perform a standard method. It is a much less extensive process than validation. The laboratory simply needs to verify that it can achieve the performance characteristics that are specified in the method. This typically involves a more limited set of experiments, such as a precision and accuracy study.

The Bottom Line

If you are using a standard method within its intended scope, you need to perform a method verification. If you are using a non-standard method, or have modified a standard method, you need to perform a full method validation. In either case, you must have objective evidence to demonstrate that your method is fit for purpose.