ISO 6353-3:1987

Overview

ISO 6353-3:1987 - "Reagents for chemical analysis - Part 3: Specifications - Second series" is an ISO monograph that specifies identity, purity and test requirements for a second series of chemical reagents used in analytical chemistry. The document provides individual reagent monographs (R41–R97) that define assay limits, impurity limits, preparation of test solutions and the tests or instrumental methods to verify conformity. It is intended to be read together with ISO 6353-1, which contains the general test methods (GM) referenced throughout.

Key topics and technical requirements

• Structured reagent monographs: Each reagent entry (for example, R41 Acetic anhydride; R42 Ammonium iron(II) sulfate; R44 Ammonium nitrate) includes specification items such as assay (purity) and limits for residues, chlorides, sulfates and metallic impurities.
• Quantitative limits: The standard sets numerical acceptance criteria for purity and impurities (e.g., many reagents specify ≥99% or ≥97% assay minima and defined maximums for chloride, sulfate or heavy metals).
• Required tests and preparation: Monographs describe how to prepare test solutions and invoke general methods (GM) for testing - examples include titration methods, residue-after-evaporation, pH measurement and color-matching procedures.
• Instrumental methods referenced: Where applicable, the standard references AAS (atomic absorption spectrometry, GM 29), FES (flame emission spectrometry, GM 30), pH measurement (GM 31) and photometric matching methods (including special instructions for iron determinations referring to ISO 6685).
• Use of Standard solutions and indicators: The document prescribes standard matching solutions (SS), reagent solutions (RS) and indicator solutions (IS) for consistent verification of reagent quality.

Applications and typical users

ISO 6353-3 is directly relevant to:

• Analytical laboratories (pharmaceutical, environmental, food and academic labs) for quality control of reagents used in quantitative analyses.
• Chemical reagent manufacturers and suppliers who need to certify lot quality against internationally recognized reagent specifications.
• Accreditation bodies and testing laboratories that perform incoming inspection or conformity assessment of analytical-grade chemicals.
• Procurement and laboratory managers who specify reagent quality requirements in contracts and SOPs.

Practical benefits include consistent reagent quality, reproducible analytical results, reduced inter-lab variability and support for regulatory or accreditation requirements.

Related standards

• ISO 6353-1 - General test methods referenced throughout ISO 6353-3.
• ISO 6353-2 - First series of reagent specifications (continued numbering).
• ISO 6685 - Referenced for specific iron determination procedures.

Keywords: ISO 6353-3, reagents for chemical analysis, reagent specifications, assay limits, impurity limits, analytical chemistry, test methods, AAS, titration, quality control.