ISO 16703:2004

Overview

ISO 16703:2004 specifies a laboratory method for the quantitative determination of mineral oil/hydrocarbon content in field‑moist soil samples by gas chromatography. The method targets hydrocarbons in the carbon range C10–C40 (boiling range approximately 175 °C to 525 °C) and is reported as mass fraction on a dry‑matter basis. Typical working concentrations are 100 mg/kg to 10 000 mg/kg soil, with options to adapt to lower detection limits.

Keywords: ISO 16703, soil quality, hydrocarbon C10–C40, gas chromatography, mineral oil determination, soil hydrocarbon analysis

Key topics and technical requirements

• Scope: Applicable to n‑alkanes C10–C40, isoalkanes, cycloalkanes, alkylbenzenes, alkylnaphthalenes and PACs that are not retained on the clean‑up column. Not applicable for gasoline‑range hydrocarbons (< C10).
• Extraction: Mechanical shaking or sonication using acetone / n‑heptane (2+1); optional alternative non‑polar solvents may be used if validated.
• Clean‑up: Florisil adsorption column (2 g Florisil + 2 g anhydrous Na2SO4) to remove polar interferences.
• Chromatography: Capillary GC with non‑polar stationary phase and flame ionization detection (FID). Preferred injection: on‑column or programmable temperature vaporization (PTV). Column recommendations: 10–25 m length, 0.10–0.32 mm i.d., film thickness 0.1–1.0 µm; column must resolve n‑alkanes in the system standard.
• Calibration and controls: External hydrocarbon calibration (mixed mineral oils) prepared in a retention‑time window (RTW) solution using n‑decane and n‑tetracontane; system‑performance standard of even n‑alkanes (C10–C40) to verify resolution and retention times.
• Sample handling: Collect per ISO 10381‑1, store sealed in darkness ≈4 °C (or ≤ −18 °C long‑term), homogenize prior to analysis. Typical extraction: ~20 g sample, 1 h extraction, aqueous washes to remove acetone, then Florisil clean‑up.

Applications and users

• Environmental testing laboratories performing soil contamination assessment and monitoring.
• Remediation consultants and operators verifying mineral oil pollution or tracking cleanup progress.
• Regulatory bodies and contract laboratories enforcing soil quality criteria and reporting hydrocarbon mass fractions.
• Research groups studying hydrocarbon fate in soils.

Related standards

• ISO 10381‑1 - Soil sampling guidance
• ISO 11465 - Determination of dry matter and water content (gravimetric)
• ISO 14507 - Pretreatment of samples for organic contaminants
• ISO 8466‑1 - Calibration and evaluation of analytical methods

ISO 16703 is a practical, GC‑based protocol widely used for reliable quantification and qualitative characterization (boiling‑range estimation from chromatogram pattern) of medium‑ and heavy‑range hydrocarbons in soils.