ISO 5093:2021

Overview

ISO 5093:2021 specifies quality characteristics for the essential oil of lemon myrtle (Backhousia citriodora F. Muell.), citral type. The standard is intended to facilitate consistent assessment of identity, purity and quality for commercial, analytical and regulatory use. Key measurable properties include physical constants, chromatographic profile (gas chromatography), carbonyl content expressed as citral, flash point guidance and requirements for sampling, packaging and labelling.

Key topics and requirements

• Identity and appearance
  • Clear, mobile liquid at 20 °C; pale yellow to yellow; characteristic lemon odour.
• Physical constants
  • Relative density at 20 °C: 0.880–0.910 (ISO 279).
  • Refractive index at 20 °C: 1.484–1.491 (ISO 280).
  • Optical rotation at 20 °C: −1.5° to +1.5° (ISO 592).
• Solubility
  • Miscibility in ethanol: oil must completely dissolve in three volumes of 70% ethanol at 20 °C (ISO 875).
• Carbonyl (citral) content
  • Carbonyl value expressed as citral; standard requires a high citral proportion (see chromatographic profile).
• Chromatographic profile (normative)
  • Gas chromatography analysis per the ISO 11024 series. Representative component ranges include:
    • Neral: 36.0–44.0%
    • Geranial: 44.0–56.0%
    • Total citral: 80.6–98.0%
    • Other minor components and limits are specified (e.g., myrcene, linalool, isocitrals).
  • The chromatographic profile is normative for conformity assessment.
• Sampling and packaging
  • Sampling per ISO 212; minimum test sample volume 50 ml.
  • Packaging, labelling and storage per ISO/TS 210 and ISO/TS 211.
• Flash point
  • Informative mean value: +99 °C (closed cup method), provided for safety and transport considerations.

Applications and users

ISO 5093:2021 is used by:

• Essential oil producers and distillers to specify product quality.
• Quality control and analytical laboratories performing GC profiling and physico-chemical tests.
• Buyers, traders and exporters/importers for contract specifications and conformity checks.
• Perfumery, flavor, cosmetic, aromatherapy and pharmaceutical manufacturers requiring consistent Backhousia citriodora citral-type raw material.
• Regulatory bodies, transport and safety personnel (flash point information) and standards organizations.

Practical benefits include standardized testing methods, reliable identity and purity criteria for lemon myrtle oil, improved traceability and reduced trade disputes.

Related standards

• ISO 11024 (chromatographic profiles), ISO 279, ISO 280, ISO 592, ISO 875, ISO 1271, ISO 212, ISO/TS 210, ISO/TS 211.