Overview
ISO 78-2:1999 - Chemistry - Layouts for standards - Part 2: Methods of chemical analysis provides a recommended layout and drafting principles for writing methods of chemical analysis in International Standards. It guides the structure, wording and presentation of test methods so they are clear, consistent and easily usable across laboratories and standards documents. The publication is intended primarily for standards developers but is also useful for test laboratories and organizations that prepare or use chemical test methods.
Key topics and requirements
- Scope and purpose: Defines the principles applicable to the layout and wording of analytical methods and notes that the layout is for guidance and may be adapted to particular needs.
- Clause structure and preferred order: Recommends a standard clause order (Foreword, Introduction, Title, Warnings, Scope, Normative references, Definitions, Principle, Reactions, Reagents and materials, Apparatus, Sampling, Procedure, Calculation, Precision, Quality assurance and control, Special cases, Test report, Annexes, Bibliography).
- Normative references: Points to related standards that form part of the normative framework (for example, ISO 31, ISO 1000, ISO 5725 and ISO/IEC Directives, Part 3).
- Terminology and definitions: Provides definitions for terms such as laboratory sample, test portion, standard solution, precision, repeatability, reproducibility and related limits.
- Quantities, units and symbols: Advises use of SI units and recommendations from ISO 31/ISO 1000 and avoidance of ambiguous abbreviations (ppm, ppb).
- Writing practice: Recommends use of IUPAC chemical nomenclature, consistent reagent names, clear numerical tolerances where critical, and prominent safety warnings when hazards exist.
- Precision and accuracy: Emphasizes reporting and defining precision (repeatability/reproducibility) and accuracy following ISO 5725 principles.
- Annexes and explanatory notes: Annex A is normative and contains application notes; other annexes may be informative.
Applications and users
- Standards bodies and technical committees drafting analytical methods (e.g., ISO/TC 47 Subcommittee SC 1).
- Laboratories and quality managers implementing or validating test procedures to ensure consistent reporting and traceability.
- Regulatory agencies and industry seeking harmonized test method presentation to simplify compliance and comparison.
- Instrument and reagent manufacturers who supply methods or method-specific documentation.
Using ISO 78-2 helps produce harmonized, searchable, and safer chemical analysis standards that facilitate reproducibility, quality assurance and international adoption.
Related standards
- ISO/IEC Directives, Part 3 (drafting of International Standards)
- ISO 31, ISO 1000 (quantities and units)
- ISO 5725 (accuracy, precision)
- Other parts of ISO 78 (Part 3: molecular absorption spectrometry; Part 4: atomic absorption spectrometric analysis)
