Analytical methods knowledge base
Analytical Method Validation: Fitness for the Intended Purpose
How specificity, range, accuracy, precision and other performance characteristics are selected around the analytical question rather than treated as a generic checklist.
Method-aware interpretation
Read the result as a chain of evidence.
Each section connects the analytical question, reporting basis and conclusion boundary.
Define what the method must decide
ICH Q2(R2) frames validation around fitness for the intended purpose. An identity test, quantitative assay, impurity method and limit test do not require identical evidence. The analytical target profile, sample matrix, reportable range and decision threshold guide which performance characteristics matter.
- State the analyte, matrix, attribute and reportable result.
- Define the range and expected decision point before validation.
- Link the performance criteria to the consequence of an incorrect result.
Use performance characteristics as evidence
Specificity or selectivity addresses interference; accuracy addresses closeness to an accepted value; precision addresses agreement among repeated measurements; range and response establish where the procedure performs as intended. Detection or quantitation limits matter when low-level decisions are required.
- Evaluate characteristics over the relevant range, not only at one convenient level.
- Use suitably characterized reference materials.
- Document calculation methods, exclusions and deviations.
Validation is not permanent immunity from change
Columns, instruments, software, sample preparation and product composition can change method performance. A lifecycle approach evaluates changes according to risk and keeps the procedure, controls and records aligned with current use.
- Assess transfer, verification or revalidation needs when the laboratory or method changes.
- Trend suitability and investigation data for evidence of drift.
- Do not cite a validation summary for a materially different procedure without justification.
Decision table
What the field means—and what it does not prove
Use this table to prevent a valid analytical result from being expanded beyond its intended purpose.
↔ Swipe horizontally to read every column
| Record or question | What it can support | What it does not prove |
|---|---|---|
| Specificity/selectivity | Ability to measure the target in the presence of relevant components | Accuracy or precision across the range |
| Accuracy and precision | Bias and repeatability/intermediate precision for quantitative results | Identity unless the procedure is designed for it |
| Reportable range | Interval over which suitable performance is demonstrated | Performance outside that interval |
Interpretation limits
Stop where the method stops.
- A method described as “validated” still needs an applicable scope and version.
- Compendial procedures may require verification for the actual conditions of use.
- Validation does not justify acceptance criteria that are scientifically inappropriate.
Primary and technical sources
Records used for this guide
Sources are linked directly so the wording, date and scope can be checked independently.
- 01Source record
ICH Q2(R2): Validation of Analytical Procedures
International Council for Harmonisation. Step 4, adopted November 2023; error-corrected 2025.
- 02Source record
Analytical Procedures and Methods Validation for Drugs and Biologics
U.S. Food and Drug Administration. Guidance for Industry, July 2015.
- 03Source record
ICH Q6A: Specifications—Test Procedures and Acceptance Criteria
International Council for Harmonisation. Step 4 guideline, October 1999.
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