ISO 4728:2003

Overview

ISO 4728:2003 is an International Standard that defines quality characteristics and test requirements for Oil of Spanish wild marjoram (Thymus mastichina L.). Its purpose is to provide reproducible criteria to assess and describe this essential oil for trade, quality control and regulatory use. The standard specifies physical properties, chromatographic composition and test methods (by reference) to facilitate consistent evaluation across laboratories and suppliers.

Key topics and technical requirements

• Scope: Characteristics of essential oil obtained by steam distillation of flowering tops of Thymus mastichina L. grown in Spain.
• Physical and sensory properties:
  • Appearance: liquid
  • Colour: almost colourless to yellow
  • Odour: characteristic, cineolic and spicy
• Measured properties and limits:
  • Relative density at 20 °C (d20): min 0.890 - max 0.920
  • Refractive index at 20 °C (n20): min 1.460 - max 1.470
  • Optical rotation at 20 °C: between –4° and +6°
  • Miscibility in ethanol 70% (v/v) at 20 °C: requirement to obtain a clear solution using up to 3 volumes ethanol per 1 volume oil (opalescence may occur)
  • Acid value: maximum 2
• Chromatographic profile (normative): Gas chromatography analysis is required. Representative components and their percentage ranges define the oil’s profile:
  • 1,8‑Cineole: 30–68% (dominant component)
  • Linalol: 3–48%
  • α‑Pinene: 1–4.5%
  • β‑Pinene: 2–5%
  • Limonene: 1–6%
  • Camphor: 0.1–2%
  • Other constituents: δ‑Terpineol, borneol, terpinen‑4‑ol, linalyl acetate, β‑caryophyllene (with specified min/max)
• Flashpoint (informative): Mean reported value +59 °C (Setaflash method referenced in Annex B).
• Sampling & test preparation: Sampling follows ISO 212; minimum test sample volume 25 ml. Test methods reference ISO standards (ISO 279, 280, 592, 875, 1242, ISO 11024-1/2).

Applications and users

ISO 4728:2003 is used by:

• Essential oil producers and distillers for product specification and acceptance criteria
• Analytical and QC laboratories performing gas chromatography and physico-chemical testing
• Fragrance, cosmetics and aromatherapy manufacturers verifying raw-material conformity
• Traders, buyers and regulatory bodies for contract specification, labelling and transport safety (flashpoint information)
• Research groups characterizing Thymus mastichina chemotypes

Related standards

• ISO 212 (Sampling), ISO 279 (Relative density), ISO 280 (Refractive index), ISO 592 (Optical rotation), ISO 1242 (Acid value), ISO 11024‑1/2 (chromatographic profile guidance), ISO/TR 210 / ISO/TR 211 (packaging and labelling), ISO/TR 11018 (flashpoint guidance).

Keywords: ISO 4728, Spanish wild marjoram oil, Thymus mastichina, essential oil standard, chromatographic profile, 1,8‑cineole, relative density, refractive index, quality assessment.