ISO 24538:2008

Overview

ISO 24538:2008 specifies a laboratory method for the determination of residual vinyl chloride monomer (VCM) in homopolymer and copolymer resins of vinyl chloride (PVC). The standard is based on a static headspace gas‑chromatographic technique with flame‑ionization detection (GC‑FID) and is performed directly on PVC in dry powder form. It is intended for routine quality control, regulatory testing and safety verification of unfilled PVC resins.

Key topics and technical requirements

• Measurement principle: static headspace analysis - vapour in equilibrium with the solid powder at a fixed temperature is injected into a GC and analyzed by FID.
• Apparatus: gas chromatograph with automatic static headspace sampler (or manual injection), suitable GC column(s), FID, 10 ml and 22 ml glass vials with PTFE‑faced septa, gastight syringes, analytical balance (0.1 mg readability), and high‑purity carrier and FID gases.
• Thermal conditioning: vials are equilibrated at 120 °C for 15 minutes before injection to reach headspace equilibrium.
• Procedures: two validated procedures are described:
  • Procedure A: uses 2–4 g test samples and calibration by spiking VCM into VCM‑free PVC; suitable down to about 0.01 mg/kg.
  • Procedure B: uses ~0.20 g test samples in 10 ml vials and external gas standards for calibration.
• Calibration and calculation: methods to prepare calibration standards (diluted or pure VCM), to correct for headspace volume and added gas, and to compute response factors and final VCM content (mg/kg).
• Safety: warns that vinyl chloride is flammable and calibration preparation should be done under a well‑ventilated hood.
• Supporting content: sections on sampling, precision, and test reporting; Annex A lists example GC columns.

Applications and who uses it

ISO 24538:2008 is used by:

• PVC resin manufacturers for quality control and release testing.
• Independent analytical and polymer testing laboratories performing residual monomer analysis.
• Regulatory and compliance labs verifying product safety and ensuring residual VCM levels meet workplace and product regulations.
• R&D groups developing new vinyl chloride homopolymers or copolymers requiring validated quantification of residual monomer.

Practical benefits include reproducible, sensitive measurement of residual VCM in powder resins, enabling process control, product safety checks and documentation for compliance.

Related standards

• ISO 6401 - referenced for compounded materials, granulates and films (dissolution required for headspace equilibrium).
• ISO 472 - vocabulary for plastics terminology used in the document.