ISO 6468:1996 PDF

Overview

ISO 6468:1996 specifies a laboratory method for the determination of certain organochlorine insecticides, polychlorinated biphenyls (PCBs) and chlorobenzenes (excluding mono‑ and dichlorobenzenes) in drinking water, groundwater, surface water and wastewater. The procedure uses liquid–liquid extraction followed by gas chromatography (GC) with an electron‑capture detector (ECD). It is intended for samples containing up to 0.05 g/L suspended solids and is aimed at environmental monitoring where very low concentrations are expected.

Key topics and technical requirements

• Scope and limits: Applicable to specified organochlorine compounds; results report specific PCB congeners (not total PCBs). Typical method detection limits reported in the standard range approximately 1–50 ng/L, depending on the compound.
• Sample handling: Collect samples in cleaned brown glass bottles, store in the dark at about 4 °C, adjust pH to 5–7 where required; special handling (acidic preservation) for sensitive compounds such as endosulfan.
• Extraction: Liquid–liquid extraction performed in the sample container (or with stirring and microseparator), using extraction solvents such as hexane, petroleum ether or heptane. Example extraction volumes: initial 30 mL followed by 20–30 mL extractions.
• Clean‑up and concentration: Drying with anhydrous sodium sulfate, optional freeze‑thaw steps, and column clean‑ups using alumina, alumina/silver nitrate, or silica gel as described. Concentration performed using evaporators (e.g., Kuderna‑Danish).
• Instrumentation: GC with ECD suitable for capillary columns (25–60 m length,