ISO 11337:2023

Overview

ISO 11337:2023 - Plastics - Polyamides - Determination of ε‑caprolactam and ω‑laurolactam by gas chromatography (GC) specifies validated laboratory methods for measuring these residual lactams in polyamides. The standard is targeted particularly at polyamide 6 (PA6) for ε‑caprolactam and polyamide 12 (PA12) for ω‑laurolactam. It defines two variants of the basic GC method: Method A (boiling methanol extraction) and Method B (dissolution/solvent method).

Key Topics

• Scope and purpose: Determination of volatile lactam monomers in polyamides using GC for quality control and compliance.
• Two methods:
  • Method A - Extraction with boiling methanol (extract injected into GC). Typical extraction: 3 h ± 5 min. Internal standards such as 1‑dodecanol or isopropanol are used.
  • Method B - Dissolution/solvent method (solution injected into GC); specific procedures for internal standards and calibration are given.
• Sample preparation: Grinding at low temperature, fraction collection through sieves (710 µm and 500 µm), and recommended test portion masses.
• Apparatus and reagents: Soxhlet-type/extraction apparatus, analytical balance, liquid nitrogen or dry ice if needed, methanol solvent, certified reference lactams.
• Gas chromatography details:
  • Both packed and capillary columns are allowed.
  • Example packed-column operating conditions with an FID detector (from the standard): column 200 °C, injector 250 °C, detector 250 °C; carrier gas helium or nitrogen.
  • Detector selection criteria: high sensitivity, linear response across measurement range.
• Calibration, internal standards, evaluation: Procedures for preparing calibration and internal‑standard solutions, peak evaluation and expression of results.
• Quality elements: Precision data, solvent recovery, and test-report requirements are specified.

Applications

• Routine quality control of PA6 and PA12 production to quantify residual monomer content.
• Material certification for manufacturers and suppliers of polyamide resins and compounds.
• R&D and process optimization to monitor polymerization efficiency and residual monomer removal.
• Regulatory and safety assessments where residual lactams affect product compliance, migration, or consumer safety.
• Use in laboratory accreditation and inter-laboratory comparisons where standardised GC methods are required.

Who should use this standard

• Polymer testing laboratories and QA/QC teams
• Polyamide resin and compound manufacturers
• Materials scientists and analytical chemists working with engineering plastics
• Regulatory bodies and conformity assessment organizations

Related standards

• ISO 472 - Plastics - Vocabulary
• ISO 565 - Test sieves - Metal wire cloth, perforated metal plate and electroformed sheet - Nominal sizes of openings

Keywords: ISO 11337:2023, polyamides, ε‑caprolactam, ω‑laurolactam, gas chromatography, Method A extraction, Method B dissolution, polyamide 6, polyamide 12, GC analysis, internal standard.