ISO 9377-2:2000

Overview

ISO 9377-2:2000 specifies a laboratory method for determining the hydrocarbon oil index in water by solvent extraction and gas chromatography (GC‑FID). Applicable to surface water, waste water and sewage treatment plant effluents, the method detects hydrocarbon oil concentrations above 0.1 mg/L. The procedure combines solvent extraction, Florisil clean‑up, capillary gas chromatography on a non‑polar column and flame ionization detection, with quantification against an external mineral‑oil standard mixture.

Key topics and technical requirements

• Analyte definition (GC‑FID hydrocarbon oil index): sum of compounds extractable with hydrocarbon solvent, boiling roughly between n‑decane (C10) and n‑tetracontane (C40) and not adsorbed on Florisil.
• Sample types and limits: suitable for surface water, waste water and sewage plant water; not intended for quantitative volatile mineral‑oil measurement; animal/vegetable fat should be <150 mg/L to avoid clean‑up overload.
• Sampling & preservation: follow ISO 5667‑3; store samples at ~4 °C and extract within four days; acidify to pH 2 when appropriate.
• Extraction & clean‑up: extracting solvent with boiling range 36–69 °C; clean up on Florisil to remove polar co‑extractives; use sodium or magnesium sulfate to prevent emulsions.
• Gas chromatography: non‑polar fused‑silica capillary column (typical length 5–30 m, i.d. 0.25–0.53 mm, film 0.25–1.2 μm) and flame ionization detector (FID); total area integrated between n‑decane and n‑tetracontane.
• Calibration & quality control: external calibration with a two‑type mineral oil mixture (type A discrete peaks, type B unresolved background); calibration curve recommended across multiple levels; QC recoveries typically required between 80 % and 110 %.
• Interferences: low‑polarity halogenated hydrocarbons, high concentrations of polar substances and surfactants can interfere with extraction and GC results.

Applications

• Environmental monitoring of rivers, lakes and coastal waters for mineral‑oil pollution
• Compliance testing of wastewater discharges and treatment plant effluents
• Forensic or incident response testing after spills to characterize hydrocarbon contamination
• Laboratory method validation and performance checks using supplied system performance tests and annex chromatograms

Who uses this standard

• Environmental laboratories performing routine water quality analysis
• Regulatory agencies and compliance laboratories
• Water utilities and wastewater treatment operators
• Consultants and researchers involved in hydrocarbon pollution assessment

Related standards

• ISO 9377‑1 (solvent extraction and gravimetry alternative)
• ISO 5667‑3 (sampling - preservation and handling)
• ISO 8466‑1 (calibration and evaluation of analytical methods)
• ISO/TR 11046 (mineral oil in soils/sediments - reference)

Keywords: ISO 9377-2, hydrocarbon oil index, water quality, solvent extraction, gas chromatography, GC‑FID, Florisil, mineral oil, environmental monitoring.