Overview
ISO 19817:2017 specifies the characteristics and testing requirements for the essential oil of thyme (Thymus vulgaris L. and Thymus zygis L.), thymol type. The standard is intended to facilitate consistent quality assessment for production, trade and laboratory control by defining physical properties, chromatographic profile limits and test methods or references.
Key topics and technical requirements
- Scope: Applies to thymol-type thyme essential oil obtained by steam distillation of flowering tops of Thymus vulgaris and Thymus zygis.
- Physical characteristics:
- Appearance: mobile liquid; colour: yellow to red; odour: aromatic, phenolic, slightly spicy.
- Relative density (20 °C): 0.910–0.937 (ISO 279).
- Refractive index (20 °C): 1.494–1.504 (ISO 280).
- Optical rotation: −6° to 0° (ISO 592).
- Miscibility in ethanol 80 %: clear solution with ≤3 volumes ethanol per 1 volume oil (ISO 875).
- Chromatographic profile (normative):
- Analysis by gas chromatography per ISO 11024.
- Specified component percentage ranges include (integrator values): Thymol 35–55 %, p‑Cymene 14–28 %, γ‑Terpinene 4–13 %, Linalool 0.5–6.5 %, Carvacrol 0.5–5.5 %, plus limits for α‑Thujene, α‑Pinene, β‑Myrcene, α‑Terpinene, Terpinen‑4‑ol, β‑Caryophyllene, and others.
- The chromatographic profile is normative (mandatory).
- Flashpoint: Informative mean value +60 °C (measured with Setaflash; see Annex B and ISO/TR 11018 for guidance).
- Sampling & sample size: Sampling per ISO 212; minimum test sample 25 ml.
- Packaging, labelling and storage: Per ISO/TS 210 and ISO/TS 211.
Applications and users
ISO 19817:2017 is used by:
- Essential oil producers and distillers for product specification and batch release.
- Quality control and analytical laboratories performing GC profiling and physical tests.
- Buyers, traders and exporters/importers to verify compliance and ensure consistency in trade.
- Perfumery, aromatherapy and flavour formulators who require defined composition and purity.
- Regulatory, transport and insurance stakeholders concerned with safety data (flashpoint) and correct labelling/packaging.
Practical applications include quality assurance, supplier specification, dispute resolution in trade, formulation decisions and safety classification for transport.
Related standards
Relevant referenced standards include ISO/TS 210, ISO/TS 211, ISO 212, ISO 279, ISO 280, ISO 592, ISO 875, ISO 11024 (chromatography), and guidance documents ISO/TR 11018 and ISO/TR 21092. These provide methods for sampling, testing and labelling that complement ISO 19817:2017.