ISO 21253-1-2019 PDF

Full title and description

ISO 21253-1:2019 — Water quality — Multi-compound class methods — Part 1: Criteria for the identification of target compounds by gas and liquid chromatography and mass spectrometry. This international standard specifies mass-spectrometric identification criteria and confirmation rules for target organic compounds in water and environmental samples, to be used alongside compound‑specific analytical methods.

Abstract

ISO 21253-1:2019 defines objective criteria for identifying target compounds in water using gas chromatography–mass spectrometry (GC‑MS) and liquid chromatography–mass spectrometry (LC‑MS) techniques. The document sets out the required identification points, retention time considerations, ion/fragment selection and relative intensity requirements, mass accuracy and library match guidance, and recommended documentation and quality‑control checks to ensure reliable compound identification in multi‑compound analytical workflows.

General information

• Status: Published / Current (international standard).
• Publication date: August 2019 (Edition 1, 2019).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.060.50 — Examination of water for chemical substances.
• Edition / version: Edition 1 (2019).
• Number of pages: 21 (official ISO edition).

Scope

This part of ISO 21253 provides criteria for the mass spectrometric identification of target organic compounds in water samples and environmental matrices. It is intended to be applied together with analytical standards and methods for the determination of specific compounds; where a specific method includes identification criteria, those take precedence. The scope covers identification using GC‑MS and LC‑MS(/MS), guidance on selection of diagnostic ions/fragments, retention time confirmation, spectral matching and decision rules for declaring a compound as identified in multi‑compound class analyses.

Key topics and requirements

• Definition of identification points/criteria for GC‑MS and LC‑MS(/MS) workflows.
• Requirements for retention time confirmation and acceptable retention time windows or deviation limits.
• Selection and use of diagnostic ions/fragments and required number of identification points.
• Relative ion intensity (ion ratio) criteria and tolerance bands for confirmation.
• Mass accuracy and resolving power guidance for high‑resolution MS identifications.
• Use of library/spectral matching and minimum match-score considerations.
• MS/MS fragment confirmation strategies where applicable (product‑ion confirmation).
• Quality control and documentation requirements: internal standards, blanks, spiked samples and reporting.
• Applicability notes (practical guidance for typical molecular mass ranges and limits of identification; additional tests recommended for larger molecules).

Typical use and users

Laboratories performing environmental and water‑quality chemical analyses, regulatory agencies, method developers, contract testing laboratories, instrument vendors (method validation/support), and accreditation bodies use this standard to harmonize identification criteria in multi‑compound screening and targeted analyses. It is intended for analysts implementing GC‑MS and LC‑MS(/MS) methods for complex sample matrices and for laboratories seeking consistent confirmation rules across multiple compound classes.

Related standards

Standards and documents commonly used with ISO 21253-1 include ISO 21253‑2 (Part 2: criteria for quantitative determination using multi‑compound class methods), guidance documents on initial measurement performance characterization (for example ISO/TS guidance referenced in multi‑compound method development), ISO/IEC 17025 (laboratory competence and quality management), and national/adopted versions such as EN ISO 21253‑1 where applicable. Relevant water‑sampling series (ISO 5667) and compound‑specific analytical standards should be consulted in tandem.

Keywords

water quality; multi‑compound class methods; compound identification; GC‑MS; LC‑MS; mass spectrometry; identification criteria; ion ratios; retention time; mass accuracy; environmental analysis; confirmation rules.

FAQ

Q: What is this standard?

A: ISO 21253‑1:2019 is an international standard that provides objective criteria and decision rules for identifying target organic compounds in water samples by GC‑MS and LC‑MS techniques.

Q: What does it cover?

A: It covers identification points, retention time confirmation, selection of diagnostic ions/fragments, ion‑ratio tolerances, mass accuracy/library match guidance, MS/MS confirmation strategies, quality‑control and documentation practices for multi‑compound class analyses.

Q: Who typically uses it?

A: Environmental and water‑testing laboratories, regulatory agencies, method developers, accreditation bodies and instrument vendors use it to standardize identification/confirmation practices in multi‑analyte workflows.

Q: Is it current or superseded?

A: ISO 21253‑1 was published in August 2019 (Edition 1) and remains the published international standard. It has not been superseded as of February 28, 2026. Users should check the ISO catalogue or national standards bodies for any amendments or later editions before purchase or adoption.

Q: Is it part of a series?

A: Yes — it is Part 1 of the ISO 21253 series (multi‑compound class methods). Part 2 (ISO 21253‑2) addresses criteria for quantitative determination; other complementary documents provide methodological and laboratory performance guidance.

Q: What are the key keywords?

A: Key keywords include: water quality, multi‑compound class methods, GC‑MS, LC‑MS, mass spectrometry, identification criteria, ion ratios, retention time, environmental analysis, confirmation rules.