Overview
ISO/TS 7013:2023 - Water quality provides practical guidance and mandatory requirements for designing and running an interlaboratory trial (interlaboratory comparison) to validate new standardized analytical methods used in water analysis. Built on the principles of ISO 5725‑1 and ISO 5725‑2, the technical specification defines preconditions, organization, sample handling, statistical evaluation and reporting needed to generate reliable performance data (repeatability, reproducibility, recovery).
Key topics and requirements
- Purpose: Final validation step to demonstrate a method is fit for purpose by evaluating performance across multiple laboratories.
- Preconditions: Method development and internal validation (e.g., per ISO/TS 13530) must be completed before the interlaboratory trial. Participants must follow the standardized protocol without technical alterations.
- Participation:
- Minimum statistical requirement: at least 24 outlier‑free results from at least eight laboratories; organisers are advised to register ≥12 laboratories to allow for attrition.
- Preferably global participation from at least five countries; participation is voluntary but organisers should select experienced labs or offer training.
- Call for participants should be issued no later than five months before sample dispatch; interested labs should respond within four weeks.
- Samples and replicates:
- Use real or spiked real samples where possible; matrices and concentration levels must reflect the method scope.
- Organisers supply all samples and replicates. Each lab should perform preferably ≥3 replicates per sample.
- Ensure homogeneity and stability of subsamples for the analysis period (methods referenced in ISO 13528).
- Provide a hidden quality control standard/extract to verify calibration; predefined tolerances guide exclusion of poor performers.
- Method options: Non‑crucial alternatives (e.g., extraction variants) can be documented and pooled if experts confirm equivalence; crucial changes (e.g., changing GC‑MS to LC‑MS) are not permitted within the same trial.
- Statistics and reporting: Organisers must define statistical evaluation, outlier handling and documentation to derive performance characteristics such as reproducibility and recovery rate.
Applications
- Validation of standardized analytical methods for drinking, surface, wastewater and environmental water analysis.
- Establishing method performance data for regulatory standards, standard development bodies, and method publishers.
- Supporting method acceptance in inter‑laboratory contexts where repeatability, reproducibility and recovery metrics are required.
Who should use this standard
- Standards development committees and method authors
- Laboratory managers and quality managers organizing method validation trials
- Accredited testing laboratories preparing to participate in method validation
- Regulatory agencies and accreditation bodies assessing method fitness-for-purpose
Related standards
- ISO 5725‑1, ISO 5725‑2 - Accuracy, repeatability and reproducibility principles
- ISO 13528 - Statistical methods for proficiency testing (homogeneity/stability guidance)
- ISO/IEC 17043 - Proficiency testing (different scope: proficiency testing, not method validation)
- ISO/TS 13530 - Validation of individual measurement process steps
Keywords: ISO/TS 7013:2023, interlaboratory trial, method validation, water quality, interlaboratory comparison, reproducibility, repeatability, assigned value, recovery rate, sample homogeneity, statistical evaluation.