ISO 6384:1981

Overview

ISO 6384:1981 - "Surface active agents - Technical ethoxylated fatty amines - Methods of analysis" specifies laboratory test methods for technical ethoxylated fatty amines (surfactants). The standard defines a battery of analyses performed on separate test portions to characterise product quality and composition, including apparent pH in methanolic medium, water content, distribution of primary/secondary/tertiary amines, oxyethylene groups content, sulphated ash, and isolation and examination of free polyethylene glycols (including verification of absence of nitrogen and determination of their relative molecular mass).

Key topics and technical requirements

• Apparent pH (methanolic medium): Potentiometric measurement using a glass or combined electrode in a 50/50 water–methanol medium; calibration with methanolic standard buffers; results reported to 0.1 pH unit at 20 °C.
• Water content: Determination by the Karl Fischer method in accordance with ISO 4317.
• Primary / secondary / tertiary amine distribution: Chemical derivatization (Schiff‑base formation with salicylaldehyde), followed by potentiometric titration in non‑aqueous solvent to evaluate total, secondary + tertiary and primary alkalinity; tertiary alkalinity is determined after acetylation and selective titration.
• Oxyethylene (ethylene oxide) groups: Determined using the method referenced in ISO 2270, with correction considerations for nitrogen‑containing products (secondary/tertiary amines can affect decomposition steps).
• Sulphated ash: Gravimetric determination referenced to ISO 4322 to quantify inorganic residue on combustion.
• Free polyethylene glycols (PEGs): Isolation from aqueous or methanolic test solutions; separated PEGs are checked for absence of nitrogen and their relative molecular mass is determined (ISO 6384 requires these checks though the extract does not specify the particular molecular‑weight technique).

Practical applications and users

ISO 6384:1981 is intended for:

• Quality control laboratories in surfactant and detergent manufacturing
• R&D teams developing ethoxylated fatty amine formulations
• Regulatory and compliance testing where compositional data (amine distribution, EO content, water, ash) affect performance, safety or labeling
• Procurement and materials specification teams who need standardised test methods for incoming raw materials

The standard supports batch release, stability assessment and troubleshooting of product performance (e.g., pH‑sensitive applications, water content affecting shelf life, or EO content influencing hydrophilicity).

Related standards

• ISO 2270 - Ethylene oxide adducts (oxyethylene groups determination)
• ISO 4317 - Water content - Karl Fischer method
• ISO 4322 - Sulphated ash - Gravimetric method
• ISO 607, ISO 4326, ISO 4327 - Additional surface‑active agent test methods referenced by ISO 6384

Keywords: ISO 6384:1981, surface active agents, technical ethoxylated fatty amines, methods of analysis, apparent pH, Karl Fischer, oxyethylene groups, primary secondary tertiary amines, sulphated ash, polyethylene glycols, potentiometric titration.