Overview
ISO 6427:2025 - Plastics - Determination of matter extractable by organic solvents (conventional methods) specifies standardized laboratory procedures to measure the amount and nature of material in plastics that can be extracted by hot organic solvents (near their boiling points) and by a defined cold-extraction method. Extractable matter includes monomers, oligomers, polymers, plasticizers, stabilizers and other additives that influence plastic properties. The standard explicitly excludes plastics intended to contact food or drinking water and is not intended for migration testing.
Key topics and technical requirements
- Scope and purpose: Determines components extractable by hot organic liquids and by a cold-extraction technique; useful for quality assessment and material characterization.
- Extraction methods: Primary method uses Soxhlet-type (or equivalent, e.g., Twisselmann) extractors; a special cold-extraction procedure is specified in Annex B.
- Extraction liquids: Selection of AR-grade organic solvents depends on plastic type and test purpose (see Table 1). Extracted amounts are often not fully quantitative for specific constituents.
- Sample preparation: Grinding or cutting to specified particle size; films <0.5 mm may be cut into fragments. Samples must be free from dust/contaminants.
- Apparatus and instruments: Soxhlet or equivalent extractor, reflux condenser, explosion-proof heating device, rotary evaporator or distillation column, vacuum oven (accurate ±2 K), analytical balance (0.1 mg accuracy), desiccator. Choice of thimble, wire basket or glass-filter crucible is important.
- Procedure controls: Pre-drying of thimbles/crucibles at 105 °C, controlled syphoning rate, specified extraction time/number of cycles (Table 1), drying conditions for residue and extract (Table 2).
- Expression of results: Calculations for total extractable matter (including volatiles) and non-volatile extractable matter, with repeat testing when replicated results differ by >5% relative.
- Precision and reporting: Interlaboratory precision not established; an approximate single-laboratory precision of ±5% may be expected. Test reports must reference ISO 6427:2025 and record sample ID, method details (extraction liquid, time, drying), and individual values.
Applications and users
- Who uses it: QC laboratories, polymer testing labs, material scientists, product developers, conformance testing facilities, and standards organizations.
- Practical uses: Incoming material inspection, formulation development, failure analysis, verifying additive content and stability, comparative evaluation of batches or substitutes. Note: not a substitute for migration or food-contact regulatory testing.
Related standards
Normative and related references include ISO 308, ISO 383, ISO 565, ISO 1773, and ISO 1875 - these provide associated test-method and apparatus specifications referenced by ISO 6427.
Keywords: ISO 6427, extractable matter, plastics testing, organic solvents, Soxhlet extraction, cold-extraction, plasticizers, monomers, polymer analysis, quality control.