Overview
ISO 21253-2:2019 - Water quality - Multi-compound class methods - Part 2 - defines criteria for developing in‑house, mass spectrometry‑based methods to quantitatively determine multiple subgroups of organic substances in water. It supplements ISO/TS 13530 by adding practical requirements for selecting the test matrix, choosing internal and injection standards, assessing analyte and internal standard recoveries, and verifying limit of quantification (LOQ) and measurement performance. This standard is intended as an additional characterization resource, not a replacement for dedicated analytical standards for individual organic compounds.
Key topics and technical requirements
- Scope and principle: Criteria for multi‑compound class analytical methods using mass spectrometry; use of a rating‑scale to assign a reliability score per compound.
- Matrix selection: Require characterization of a representative matrix (natural or synthetic) defined by physicochemical properties (SPM, TOC, conductivity, pH, major ions). Laboratory‑grade water is not representative.
- Sample preservation: Define and verify storage time and preservation procedures from collection through analysis; test preservation on the representative matrix (near 10× LOQ or regulatory value).
- Internal and injection standards: Internal standards must be added at the start of sample preparation; isotopically labelled standards are recommended. Injection standards monitor instrument response and recovery.
- Calibration and quantification: Guidance on external vs. internal calibration approaches and requirements for calibration curves and verification.
- Recovery and yield assessment: Criteria for determining analyte recovery, internal standard recovery, and yield accounting for matrix effects and any purification steps.
- Limit of quantification (LOQ): LOQ definition and verification in the intended matrix.
- Quality controls and reporting: Routine QA checks on blanks, internal standards, LOQ, identification, quantification and measurement uncertainty.
Applications and users
ISO 21253-2:2019 is practical for:
- Environmental and water quality laboratories developing or validating multi‑compound MS methods (GC‑MS, LC‑MS) for screening and quantification of organic contaminants.
- Method developers creating in‑house procedures that cover many analytes across subgroups.
- Regulatory and accreditation bodies evaluating method characterization, LOQ verification, recovery performance, and routine quality control practices.
- Laboratories needing a structured approach to demonstrate reliability of compound quantification within defined water matrices.
Related standards
- ISO/TS 13530 (initial measurement performance characterization)
- ISO 21253-1 (identification criteria by chromatography and mass spectrometry)
- ISO 8466-1 / ISO 8466-2 (calibration and evaluation of analytical methods)
- ISO 11352 (estimation of measurement uncertainty)
Keywords: ISO 21253-2:2019, water quality, multi-compound class methods, mass spectrometry, internal standards, limit of quantification, analyte recovery, quality control.
Open preview (PDF)Water quality — Multi-compound class methods — Part 2: Criteria for the quantitative determination of organic substances using a multi-compound class analytical method