Method Validation
Definition
The process of demonstrating that an analytical method does what it claims: that it correctly identifies the target analyte, at what sensitivity, with what specificity, across what range of sample conditions, and with what error rate. In wildlife forensics, validation must be done separately for each taxon the method will be used on.
- Required by
- ISO 17025:2017 clause 7.2.2 and NABL Document 141
- Key accuracy target
- 80-120% recovery from known samples
- Precision standard
- Intraday RSD less than 5%, interday less than 10%
- Scope
- Must be specific to the matrix, analyte, and concentration range where the method will be used
Common questions
What does it mean to validate an analytical method in forensics?+
Method validation proves that a specific analytical procedure reliably measures what it claims to measure. You document its performance characteristics, including how accurately it identifies the target material, at what sensitivity, and with what error rate under the conditions where it will be used.
What parameters are tested during method validation?+
Labs test specificity (identifies the right target), linearity (proportional response across a concentration range with R² ≥ 0.995), accuracy (80-120% recovery of known samples), precision (intraday variation less than 5%, interday less than 10%), and the method's sensitivity limits (LOD and LOQ). Robustness is also tested to see how the method performs when conditions shift slightly.
Why is method validation required?+
Method validation is mandated by ISO 17025:2017 and similar accreditation standards. It demonstrates that the laboratory's procedures are fit for their intended purpose and can produce trustworthy results. Accreditation bodies inspect validation documentation on every visit.
Related terms
- ISO 17025
- International standard for the general requirements for the competence of testing and calibration laboratories. Covers management system requirements (document control, internal audits,...
- Measurement Uncertainty
- A quantitative statement of the range within which the true value of a measurement lies, at a stated confidence level (typically 95%,...
- Proficiency Testing
- An external quality assurance programme in which a laboratory analyses blind samples distributed by an independent provider and submits results for comparison...
- Proficiency Testing (PT)
- A quality assurance mechanism in which laboratories analyse blind samples distributed by an external scheme coordinator and have their results compared against...
- Accreditation
- Formal recognition by a standards body (such as UKAS in the UK, A2LA in the US, or NABL in India) that a...
- Accreditation Body
- A national or regional organisation that assesses laboratories against ISO/IEC 17025 and grants accreditation. Examples include UKAS (United Kingdom Accreditation Service), NIST-associated...
- Accuracy and Precision
- Accuracy is closeness to the true value, measured as recovery from a spiked CRM with the 80 to 120 percent window. Precision...
- Blank Control
- A sample known to contain none of the target material, processed in parallel with real exhibits to detect laboratory contamination. A positive...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- Control Chart
- Time-series plot of a QC measurement with warning limits at ±2σ and action limits at ±3σ from validation data. Patterns such as...
- Corrective Action and CAPA
- The ISO 17025 Clause 8.7 requirement for root-cause analysis and documented corrective and preventive action (CAPA) following any nonconformity (PT failure, IQC...
- ENFSI (European Network of Forensic Science Institutes)
- The umbrella organisation representing public forensic science laboratories across Europe. Develops best practice manuals for forensic disciplines, runs proficiency testing schemes, and...
Explained in these topics
- Accreditation and Quality Systems in Wildlife ForensicsThe process of demonstrating that an analytical method does what it claims: that it correctly identifies the target analyte, at what sensitivity, with what spe...
- ISO 17025, NABL, ENFSI and Quality Systems for Forensic Chemistry LaboratoriesThe documented process of demonstrating that an analytical method is fit for its intended purpose. Validation parameters: specificity, linearity (R² ≥ 0.995),...
- Method Validation, Measurement Uncertainty and Proficiency TestingDocumented exercise that proves a method is fit for purpose for a defined matrix, analyte and concentration range. Required by ISO 17025:2017 clause 7.2.2 and...
- Quality Assurance, Reference Collections, and AccreditationThe process of confirming that an analytical method does what it claims to do: consistently identifying the target material with defined accuracy, precision, s...
- Quality Systems: ISO 17025 and AccreditationThe process of confirming, through systematic testing, that a specific analytical procedure reliably measures what it claims to measure, with documented perfor...