ISO 787-28:2019

Overview

ISO 787-28:2019 specifies a laboratory method for the determination of total polychlorinated biphenyls (PCBs) in pigment materials. The procedure targets all 209 PCB congeners, using a dissolution approach followed by cleanup and analysis by gas chromatography–mass spectrometry (GC‑MS). The method is designed for a working range of 1 mg/kg to 150 mg/kg; the lower limit of quantitation (LOQ) is 1 mg/kg per congener (results below 1 mg/kg are qualitative).

Key topics and technical requirements

• Scope: Total PCB content in pigments/ extenders, addressing occluded PCBs not accessible to surface-only extractions.
• Sampling: Representative, dry powder samples with volatiles <1% (per ISO 15528). Store in dark, capped glass containers.
• Sample preparation:
  • Add 13C12‑labelled internal reference materials directly to the freshly weighed sample (no later additions).
  • Dissolve sample in concentrated sulfuric acid (92–95% m/m) with sonication until homogenous; keep temperature below 50 °C.
  • Optional leaching pre-step can be used for low‑chlorinated congeners.
• Cleanup:
  • Sequential wet column chromatography to remove interfering species (aryl sulfuric acids, polymers, heterocycles).
  • Multilayer columns are obligatory; optional steps include diatomaceous earth–sulfuric acid columns, gel permeation (size exclusion), and alumina columns.
• Separation and detection:
  • Final analysis by GC‑MS, preferably using SIM mode for quantitation; a 60 m column is recommended for congener separation (30 m allowed for screening).
  • Quantitation by peak area ratios of analytes to corresponding internal standards; identification uses multiple specific ion traces.
• Safety: Use analytical‑grade reagents, trained personnel, and follow PCB handling rules. UV (254 nm) is noted for spill‑decomposition procedures.

Practical applications and users

• Pigment and dye manufacturers: quality control and supplier screening to verify PCB contamination levels.
• Independent testing laboratories: routine and compliance testing for pigments and extenders used in paints, inks and coatings.
• Regulatory bodies and customs laboratories: enforcement of chemical safety limits and import/export controls.
• Paint, varnish and raw‑materials manufacturers: incoming material verification to prevent PCB introduction into formulations.
  Advantages: the dissolution approach avoids underestimating total PCB content caused by occlusion within pigment crystal lattices-common shortcomings in environmental or surface‑only extraction methods.

Related standards

• ISO 15528 - Paints, varnishes and raw materials for paints and varnishes - Sampling.
• ISO 18451-1 - Pigments, dyestuffs and extenders - Terminology (general terms).
• Part of the ISO 787 series (general test methods for pigments and extenders).

Keywords: ISO 787-28:2019, PCBs in pigments, polychlorinated biphenyls, PCB congeners, GC‑MS analysis, sulfuric acid dissolution, multilayer cleanup, 13C12 internal standard, limit of quantitation.