Overview
ISO 24329:2022 - "Low-protein natural rubber latex concentrate - Specification" defines quality and safety specifications for low-protein natural rubber (LPNR) latex concentrates. The standard targets latex suitable for medical rubber products where reduced protein levels lower the risk of latex allergy. It specifies two LPNR types: type HA (high ammonia) and type LA (low ammonia), and sets test-method references and sampling rules for consistent quality control.
Key topics and technical requirements
ISO 24329:2022 outlines measurable requirements and associated test methods (many cited as ISO test standards and ASTM D5712). Key technical parameters include:
- LPNR definition: Field or concentrated latex pretreated with deproteinising agents, centrifuged, and preserved after concentration with ammonia only (alkalinity ≥ 0.6% for HA; ≤ 0.29% for LA).
- Minimum solids/rubber content:
- Total solids: ≥ 61.0% or
- Dry rubber content: ≥ 60.0%
- Non-rubber solids: max 1.70% (difference between total solids and dry rubber content)
- Alkalinity (as NH3): Type HA ≥ 0.60%; Type LA ≤ 0.29% (mass fraction)
- Mechanical stability: ≥ 650 seconds (ISO 35)
- Coagulum content: max 0.02%
- Metal contaminants: Copper and manganese max 8 mg/kg of total solids (ISO 8053, ISO 7780)
- Sludge content: max 0.06%
- Volatile fatty acid (VFA) number: max 0.06
- KOH number: max 0.70
- Extractable protein (EP): max 100 µg/g (ASTM D5712, modified Lowry method)
- Sampling: Per ISO 123
All requirements reference standardized test methods (ISO 124, 125, 126, 127, 506, 706, 2005, etc.) to ensure reproducible measurement and compliance.
Applications
ISO 24329:2022 is directly applicable to manufacturers and suppliers of latex concentrates intended for:
- Medical rubber products (e.g., examination and surgical gloves)
- Hygienic and consumer latex goods where allergy risk must be minimized
- Downstream processors who convert concentrate into finished latex products
Using LPNR latex that meets ISO 24329 reduces extractable protein, improving biocompatibility and lowering allergic reactions while maintaining mechanical and processing properties.
Who should use this standard
- Latex concentrate producers and formulators
- Medical device and glove manufacturers
- Quality assurance and regulatory compliance teams
- Testing laboratories and procurement specialists specifying raw-material tolerances
Related standards
- ISO 24376 - Guidelines for technically specified low-protein natural rubber
- Test-method standards referenced in ISO 24329: ISO 35, 123, 124, 125, 126, 127, 506, 706, 2005, 7780, 8053 and ASTM D5712
Using ISO 24329:2022 helps organizations ensure consistent LPNR quality, improve patient and worker safety, and meet regulatory and procurement requirements for low-protein latex materials.