Overview
ISO 17494:2001 specifies a gas chromatographic method for the determination of ethanol content in aromatic extracts, flavouring and perfuming compounds. The method covers analysis on either packed columns or capillary columns and is applicable to products with presumed ethanol contents greater than 0.5 %. It defines the analytical principle (GC with an internal standard), required reagents and typical operating conditions, and refers to general GC standards for detailed procedures.
Key topics and requirements
- Scope: Ethanol determination in liquid/diluted aromatic products (excludes dry spices); applicable when ethanol > 0.5 %.
- Principle: Gas chromatography using the internal standard method (2‑propanol or n‑propanol recommended).
- Reagents:
- Reference: absolute ethanol (≥99 %), verified by ISO 760 and GC.
- Internal standard: 2‑propanol or n‑propanol (≥99 %, ethanol‑free).
- Solvent: methanol or other suitable solvent free from interfering impurities.
- Apparatus: Standard GC system with flame ionization detector (FID); packed or capillary columns as recommended:
- Packed example: 3–4 m length, 2–4 mm i.d., vinyl benzene/styrene stationary phase.
- Capillary example: 10–100 m length, 0.2–0.5 mm i.d., dimethylpolysiloxane or PEG phase.
- Operating conditions (typical):
- Packed columns: oven ~150 °C; injection/detector ~180 °C.
- Capillary columns: oven ~50 °C; injection/detector ~230 °C.
- Column performance: Chemical inertness and efficiency must be verified per ISO 7359 / ISO 7609.
- Calibration and quantification: Determine response factor relative to internal standard as specified in the referenced GC general methods.
- Precision: Repeatability-differences >5 % are expected in no more than 5 % of cases; reproducibility-differences >10 % in no more than 5 % of cases.
- Special handling: Viscous samples should be diluted in the chosen solvent before analysis.
Applications
ISO 17494 is intended for practical use in:
- Quality control laboratories in the flavor & fragrance industry and essential-oil producers.
- Contract testing and analytical service labs measuring ethanol content in aromatic extracts.
- Regulatory and compliance testing where accurate ethanol quantification in perfuming/flavouring matrices is required.
Benefits include standardized, reproducible ethanol analysis for product specification, batch release, adulteration checks, and formulation control.
Related standards
- ISO 7359 - Essential oils - GC on packed columns (general method)
- ISO 7609 - Essential oils - GC on capillary columns (general method)
- ISO 760 - Determination of water - Karl Fischer method
Keywords: ISO 17494, ethanol content, gas chromatography, packed column, capillary column, flavouring compounds, perfuming compounds, internal standard, flame ionization detector, method precision.