ISO 21627-1:2009

Overview

ISO 21627-1:2009 - Plastics - Epoxy resins - Determination of chlorine content - Part 1: Inorganic chlorine specifies a direct potentiometric titration method to measure inorganic chlorine (ionic chlorine, Cl−) in epoxy resins. Results are reported as milligrams of chlorine per kilogram of resin (mg/kg). This part is one of three in the ISO 21627 series covering inorganic, saponifiable and total chlorine in epoxy resins.

Key topics and requirements

• Scope and definition
  • Measures inorganic chlorine (chloride ion) in epoxy resins.
  • Requires laboratory practices and safety awareness; uses analytical-grade reagents and water per ISO 3696.
• Analytical principle
  • Dissolve a representative sample in an appropriate solvent (acetone typical; alternatives: methyl ethyl ketone or THF if needed).
  • Titrate directly with a 0.002 mol·L−1 silver nitrate (AgNO3) solution using potentiometric end-point detection with a combined silver/silver‑chloride electrode.
  • Determine the end-point from the inflection of potential vs. volume curve.
• Reagents and apparatus
  • Analytical reagents (acetone, isopropanol, glacial acetic acid), AgNO3 titrant prepared and calibrated, microburette, potentiometer/titrator, combined Ag/AgCl electrode, analytical balance (0.1 mg), magnetic stirrer.
• Calculation and reporting
  • Content calculated from titrant volume, titrant concentration, and sample mass; results rounded to one decimal place (mg/kg).
  • Test report must include reference to ISO 21627-1, sample identification, solvent used (if not acetone), test results and date.
• Performance (fidelity)
  • Repeatability and reproducibility established by an interlaboratory study (10 labs). Example reproducibility (R) values: 0.13 mg/kg for w(Cl) <1 mg/kg, 0.27 mg/kg for 1–3 mg/kg, 0.55 mg/kg for 3–5 mg/kg.

Applications and users

• Who uses it
  • Analytical chemists, QC/QA laboratories, resin manufacturers, materials testing labs, and compliance teams in the plastics and coatings industries.
• Use cases
  • Quality control of epoxy resins produced from epichlorohydrin to detect ionic chloride impurities.
  • Release testing, supplier qualification, troubleshooting of curing or performance issues linked to chloride contamination.
  • Supporting regulatory compliance and formulation optimization where chloride content affects final product properties.

Related standards

• ISO 21627-2: Chlore facilement saponifiable (saponifiable chlorine)
• ISO 21627-3: Chlore total (total chlorine)
• ISO 4615: Total chlorine in polyesters/epoxies
• ISO 3696: Laboratory water quality
• ISO 5725-2: Accuracy (repeatability and reproducibility)

Keywords: ISO 21627-1:2009, epoxy resins, inorganic chlorine, ionic chlorine, potentiometric titration, silver nitrate, chlorine content, plastics standard, analytical method.