Overview
EN ISO 21253-2:2019 - "Water quality - Multi-compound class methods - Part 2" provides criteria for developing and assessing in‑house mass spectrometry (MS)-based methods for the quantitative determination of multiple subgroups of organic substances in water. Published by CEN/ISO, this standard complements ISO/TS 13530 by giving practical details on selecting test matrices and internal standards and setting acceptance criteria for analyte and internal standard recoveries. It is intended as an additional resource - not a replacement for individual analytical standards for specific organic compounds.
Key topics and requirements
The standard focuses on method development and performance characterization for multi‑compound class analytical workflows, with emphasis on:
- Selection of the matrix - guidance for choosing representative test matrices for method verification and LOQ confirmation.
- Sample preservation - basic requirements for preserving water samples prior to extraction and MS analysis.
- Internal and injection standards - principles and criteria for selecting internal standards and injection standards to monitor method performance and correct for losses.
- Calibration strategies - calibration approaches applicable to external and internal calibration, including linearity considerations.
- Recovery determination - procedures and acceptance criteria for determining analyte recovery and internal standard recovery across subgroups of organic compounds.
- Limit of quantification (LOQ) - verification of LOQ in the intended matrix and related checks.
- Results and uncertainty - identification, quantification, and measurement uncertainty reporting considerations.
- Quality controls - blank checks, internal standard monitoring, LOQ validation and ongoing QC measures.
- Matrix effect (informative annex) - discussion of matrix effects on MS response and mitigation strategies.
Keywords: EN ISO 21253-2:2019, water quality, multi-compound class methods, mass spectrometry, internal standards, recovery, LOQ, calibration, matrix effect.
Practical applications and users
This standard is practical for organizations that develop or validate multi‑compound MS methods for water analysis:
- Environmental and public‑health laboratories performing routine monitoring of organic contaminants in surface water, groundwater and drinking water.
- Water utilities and contract testing labs implementing or validating in‑house LC–MS/MS or GC–MS/MS multi‑residue methods.
- Method developers and laboratory quality managers setting up QC procedures, recovery checks and LOQ verification.
- Regulatory bodies and accreditation assessors evaluating method fitness for purpose when standards for individual analytes are not prescriptive.
Related standards
EN ISO 21253-2:2019 adds specific, practical criteria for robust quantitative multi‑compound MS methods in water quality analysis, helping laboratories demonstrate reliable recoveries, calibration and LOQ verification across compound subgroups.