Overview
EN ISO 9832:2003 (ISO 9832:2002) specifies a laboratory method for the determination of residual technical hexane in animal and vegetable fats and oils. The procedure uses headspace sampling and gas chromatography (GC) with a flame ionization detector (FID) after thermal desorption. The method quantifies hexane in the range 10 mg/kg to 1 500 mg/kg and is explicitly not applicable to marine oils.
Key topics and technical requirements
- Scope and measurement range: Suitable for residual hexane between 10–1 500 mg/kg; excludes marine oils.
- Principle: Desorption of volatile hydrocarbons at 80 °C in a closed septum vial, followed by headspace sampling and GC-FID analysis (packed or capillary columns).
- Reagents:
- Technical hexane (recommended for calibration) or n‑hexane.
- Internal standard: n‑heptane (preferred) or cyclohexane (if compatible).
- Carrier and auxiliary gases (dry, low-oxygen).
- Apparatus:
- 20 mL septum vials and inert septa, thermostatted heating bath at 80 °C ± 2 °C, syringes for headspace sampling (1 000 µL warmed to 60 °C), GC with FID.
- Injector/detector typically set at 100 °C, oven at 50 °C; capillary column methods require a 1/100 split.
- Calibration and procedure:
- Prepare calibration fat with known added volumes of technical hexane (tabled concentrations).
- Add internal standard, equilibrate vials at 80 °C (60 min), withdraw headspace (1 000 µL) and inject directly to GC.
- Calculate calibration factor (mean F ≈ 0.45 for n‑heptane) and use it for sample quantification.
- Related normative references: ISO 661 (preparation of test sample); recommended sampling per ISO 5555.
Applications
- Routine testing for solvent residues in edible oils and fats after extraction or refining processes (e.g., oilseed processing, deodorization validation).
- Quality control in food manufacturing and refining to verify solvent removal.
- Analytical support for product labeling, internal HACCP/QA procedures, supplier acceptance testing.
- Use by contract testing laboratories performing headspace GC analyses for food safety and compliance.
Who uses this standard
- Food and oil industry quality assurance and analytical laboratories.
- Regulatory and food safety testing bodies verifying solvent residue levels.
- Oilseed processors, refiners, and manufacturers of edible fats and oils.
- Laboratories implementing headspace gas chromatography methods and instrument vendors supplying GC systems and consumables.
Keywords: EN ISO 9832, ISO 9832:2002, residual hexane, hexane content determination, headspace GC, fats and oils analysis, solvent residues, food quality control.
