ISO 16620-4:2024

Overview - ISO 16620-4:2024 (Plastics - Biobased content - Part 4)

ISO 16620-4:2024 specifies a laboratory method for determining the biobased mass content of plastics and plastic materials using radiocarbon analysis (14C) together with elemental analysis. Applicable to plastic products, polymer resins, monomers and additives that contain carbon, the standard requires a prior statement of the product’s elemental composition and biobased carbon content. This second edition updates procedures and normative references from the 2016 edition.

Key technical topics and requirements

• Measurement principle: Combines radiocarbon (biobased carbon fraction) and elemental analysis (C, H, N, O) to calculate biobased mass content.
• Product grouping: Distinguishes Group I (products made by chemical/biochemical/biological reactions) and Group II (mixtures of Group I products without further reaction), with specific procedures for each group.
• Rules for element allocation: Defines how hydrogen, oxygen and nitrogen are allocated to biobased mass when bound to biobased carbon structures; non CHON elements are excluded from the biobased mass calculation.
• Natural constituents: Natural polymers wholly derived from biomass are considered 100% biobased mass content; radiocarbon testing is not required.
• Monomers and additives: If composition and origin are unequivocal, determination may be limited to biobased carbon content.
• Validation, sampling and reporting: Specifies sampling guidance, variability assessment, validation criteria and formats for test reports (informative and normative annexes).
• Limitations: Isotopic analysis can distinguish biobased vs fossil carbon but cannot reliably attribute the origin of O, H or N atoms without considering their chemical linkage to carbon.

Practical applications

• Verifying biobased claims for product labeling, sustainability reporting and regulatory compliance.
• Supporting supply-chain traceability when plastics are produced from mixed biobased and fossil feedstocks.
• Providing test-lab methods for quantifying biobased mass content for circular-economy metrics and procurement specifications.
• Informing formulation decisions by R&D teams when substituting fossil-derived monomers or additives with biobased alternatives.

Who should use ISO 16620-4:2024

• Testing laboratories and accredited analytical service providers
• Plastics manufacturers, polymer chemists and formulators
• Product certifiers, ecolabel schemes and compliance officers
• Brand owners, sustainability managers and procurement teams

Related standards

• ISO 16620-1 - General principles for biobased content
• ISO 16620-2 - Determination of biobased carbon content (radiocarbon methods)
• ISO 16620-3 - Biobased synthetic polymer content (related calculations)
• ISO 16620-5 - Declaration of biobased mass content (claims)
• EN 17351 - Determination of oxygen content using an elemental analyser

Keywords: ISO 16620-4:2024, biobased mass content, radiocarbon analysis, elemental analysis, plastics, biobased carbon content, Group I, Group II.