TL;DR
- ISO/IEC 17025:2017 Clause 7.2 covers method selection, verification, and validation for testing and calibration laboratories.
- Laboratories verify standard methods before introducing them and validate methods that are non-standard, developed in-house, used outside their intended scope, or modified in ways that affect their intended application.
- Validation may assess characteristics such as precision, trueness, selectivity, working range, linearity, detection limits, and robustness, depending on the method and its intended use.
- A documented validation plan, acceptance criteria, results, deviations, and approval records help demonstrate that a method is fit for purpose.
Laboratories pursuing ISO 17025 accreditation need more than a written testing procedure. They must demonstrate that the methods they use are suitable for their intended purpose and can produce reliable results under the laboratory's actual operating conditions.
ISO 17025 method validation helps laboratories establish this evidence systematically. It defines how to evaluate a method's performance, determine whether it meets technical requirements, and document the evidence needed before routine use. Understanding the difference between validation and verification is the first step toward building a practical, assessment-ready process. For a broader view of the standard, see our ISO 17025 compliance guide.
What Is ISO 17025 Method Validation?
ISO 17025 method validation is the documented process of establishing that a laboratory method is suitable for its intended use. It involves evaluating relevant performance characteristics and comparing the results with predefined acceptance criteria.
The applicable requirements appear in Clause 7.2 of ISO/IEC 17025:2017, which addresses method selection, verification, and validation.
Validation is particularly important when a laboratory develops a new method or changes an existing procedure. The extent of the study should reflect the intended application, the risks associated with incorrect results, customer requirements, and the method's technical complexity.
Method validation vs. method verification
These terms are related but serve different purposes.
A published standard method is not automatically ready for use in every laboratory. The laboratory must still verify its ability to perform that method under its own conditions.
When is method validation required?
Under Clause 7.2.2, validation is required for methods that fall into categories such as:
- Non-standard methods.
- Methods designed or developed by the laboratory.
- Standard methods used outside their intended scope.
- Standard methods that have been modified, where the changes affect their intended application.
When a laboratory changes a previously validated method, it should evaluate the impact of the change and determine whether additional validation is necessary. The decision and supporting evidence should be documented.
Which Parameters Should ISO 17025 Method Validation Assess?
There is no single set of parameters that applies identically to every laboratory method. The appropriate characteristics depend on whether the method is quantitative or qualitative, the type of measurement, the sample matrix, and the intended use.
1. Precision
Precision describes the closeness of agreement among repeated measurements under specified conditions.
Depending on the method, a laboratory may evaluate:
- Repeatability: Results obtained under closely controlled conditions over a short period.
- Intermediate precision: Variation within the laboratory across relevant changes, such as days, analysts, or equipment.
- Reproducibility: Variation under reproducibility conditions, often involving different laboratories.
The study design should reflect the conditions that could affect routine results.
2. Trueness, bias, and recovery
Trueness concerns how closely the average of repeated measurements agrees with a reference value. Bias is the systematic difference between a measurement result and a reference value.
Depending on the method, laboratories may assess trueness using certified reference materials, reference methods, recovery studies, or other suitable comparisons.
Recovery studies can be useful when evaluating analytical methods that involve extraction, sample preparation, or measurement in complex matrices.
3. Selectivity, working range, and linearity
These characteristics help establish whether a method can reliably measure the intended analyte or property across the required operating range.
- Selectivity: Ability to distinguish the target from relevant interferences.
- Working range: Interval over which the method meets its performance requirements.
- Linearity: How well the response follows an appropriate linear relationship over a defined range, when relevant.
A method may perform well in a simple reference solution but behave differently in a real sample matrix. Validation should account for relevant interferences and sample conditions.
4. Detection and quantification limits
For methods where low-level detection matters, laboratories may need to establish a limit of detection (LOD) and limit of quantification (LOQ), using an appropriate approach for the method and its intended application.
The LOD relates to detecting the presence of a target under defined conditions. The LOQ relates to quantifying it with acceptable performance.
These limits should not be treated as interchangeable. The selected approach and resulting limits should be justified and documented.
5. Robustness and measurement uncertainty
Robustness evaluates how method performance responds to small, deliberate changes in relevant conditions, such as temperature, reagent concentration, or instrument settings.
Measurement uncertainty is also important when assessing the reliability and interpretation of measurement results. Its evaluation is addressed separately in Clause 7.6 of ISO/IEC 17025:2017.
Not every method requires every parameter listed above. Select the characteristics that are technically relevant, establish acceptance criteria before testing, and explain why the selected study is sufficient.
How to Perform ISO 17025 Method Validation: Step-by-Step
A structured validation process makes it easier to plan experiments, review results, and demonstrate technical competence during an assessment.
Step 1: Define the intended use and requirements
Document what the method measures, the sample types it covers, the required range, the expected reporting limits, and the performance needed for the intended application.
Translate customer, regulatory, or technical requirements into measurable acceptance criteria.
Step 2: Prepare a validation plan
Identify the performance characteristics to evaluate, the experimental design, sample numbers, equipment, reference materials, responsible personnel, and statistical methods.
Define acceptance criteria before conducting the study. This reduces the risk of judging results against thresholds chosen only after the data are available.
Step 3: Confirm equipment and resources are suitable
Ensure that relevant instruments are functioning correctly and that calibration, reference materials, reagents, environmental conditions, and personnel competence are appropriate for the study.
A method validation study cannot provide meaningful evidence if equipment or other critical resources are not fit for use.
Step 4: Conduct the study and evaluate results
Execute the approved plan and record raw data, calculations, observations, and any deviations. Evaluate the selected characteristics using suitable statistical or technical methods.
Compare results with the predefined acceptance criteria. If results do not meet requirements, investigate the cause, document the findings, and determine whether corrective action or further study is necessary.
Step 5: Approve the method before routine use
Prepare a validation report that summarizes the method, study design, acceptance criteria, results, conclusions, limitations, and approval.
Update the controlled method procedure where needed, following your ISO 17025 document control process. Ensure relevant staff are trained and that the approved method is available at the point of use.
ISO 17025 Method Validation Checklist and Documentation
A validation study should leave behind enough objective evidence for another qualified person to understand what was tested, how performance was evaluated, and why the method was accepted.
Use this checklist as a starting point and tailor it to the method and laboratory's scope.
- Intended use, measurands, sample types, and scope are defined.
- The reason for validation rather than verification is documented.
- A validation plan and acceptance criteria were approved before testing.
- Relevant performance characteristics and study design are justified.
- Equipment calibration, reference materials, and resource suitability are documented.
- Raw data, calculations, statistical analysis, and observations are retained.
- Deviations, unexpected results, and investigations are recorded.
- Results are evaluated against the approved acceptance criteria.
- The validation report states conclusions, limitations, and approval.
- The controlled method, staff training, and change-control records are updated as needed.
What should a method validation report contain?
A practical report typically includes the method identifier and version, scope and intended use, personnel and dates, validation plan, acceptance criteria, results, supporting calculations, deviations, conclusions, and approval.
Keep supporting evidence traceable to the method version and study that produced it. If the method changes later, the laboratory should assess the change's impact and document whether revalidation or additional verification is needed.
How Scispot Can Support Method Validation Workflows
Method validation generates technical evidence, but laboratories also need a reliable way to organize related procedures, sample data, results, and quality records.
Scispot's laboratory platform can help connect laboratory workflows, sample information, documentation, and quality processes in a more traceable environment. Depending on the configured solution, a laboratory may use a connected platform to organize method versions, associate results with the applicable procedure, and make supporting records easier to retrieve.
Software does not replace the laboratory's technical responsibility to design a suitable validation study, set scientifically justified acceptance criteria, or approve a method for use. The laboratory remains responsible for confirming that its configured workflows meet its requirements.
For laboratories evaluating digital support for ISO 17025 readiness, the goal is to make the evidence behind each method easier to maintain, review, and retrieve.
