ISO 18321:2015
(Main)Essential oils - Determination of peroxide value
Essential oils - Determination of peroxide value
ISO 18321:2015 specifies a method for the determination of the peroxide value in an essential oil. The peroxide value is a measure of the oxidation present.
Huiles essentielles — Détermination de l'indice de peroxyde
General Information
- Status
- Published
- Publication Date
- 12-May-2015
- Technical Committee
- ISO/TC 54 - Essential oils
- Drafting Committee
- ISO/TC 54 - Essential oils
- Current Stage
- 9093 - International Standard confirmed
- Start Date
- 03-Dec-2025
- Completion Date
- 13-Dec-2025
Overview - ISO 18321:2015 (Peroxide value in essential oils)
ISO 18321:2015 specifies an analytical method for the determination of the peroxide value in an essential oil. The peroxide value is a quantitative indicator of the oxidation present in an oil and is widely used in quality control to assess rancidity, storage stability and product acceptability. The method is an iodometric redox titration and can be performed by conventional volumetric titration or by potentiometric titration (recommended for highly coloured essential oils).
Key topics and technical requirements
- Principle: Iodide is oxidized by peroxides to release iodine, which is titrated with sodium thiosulfate (iodometry). End point can be detected visually with starch indicator or potentiometrically.
- Reagents and quality: Analytical-grade reagents and Grade 3 water (ISO 3696). Typical reagents include trichloromethane (chloroform) or cyclohexane, glacial acetic acid, saturated potassium iodide, and 0.01 N or 0.1 N sodium thiosulfate.
- Apparatus: Standard laboratory glassware (balance ±1 mg, 250 ml Erlenmeyer, shaker, pipettes, 10 ml burette) and optionally a potentiometer for automated titration.
- Sampling and preparation: Sampling and test-sample preparation are referenced to ISO 212 and ISO 356. Samples should be homogenized without heating/airation, tested immediately, and filtered if impurities are visible.
- Procedure: Typical test portion is 10 ml essential oil; add solvent, acetic acid and KI, shake, dilute with water, and titrate. Use 0.1 N thiosulfate when peroxide values are expected >20 mmol/l, 0.01 N for lower values. Perform a blank titration.
- Automated titration notes: Use amber autosampler vessels to prevent iodine formation; if automating KI addition, use a 70% KI solution in opaque bottles and adjust added volume.
- Results and calculation: Peroxide value is calculated from the difference between test and blank titrant volumes and titrant normality. Conversion from mmol/l to meq/kg uses a density-based factor.
- Precision: Repeatability: differences not exceeding 5% (absolute) or 0.1 (relative). Reproducibility: differences not exceeding 10% (absolute) or 0.3 (relative).
Applications and users
ISO 18321:2015 is used by:
- Quality control laboratories in the fragrance, flavor and aromatherapy industries
- Essential-oil producers and packers monitoring oxidation and shelf life
- Regulatory and testing laboratories verifying product conformity
- Analytical chemists developing stability and storage studies
Practical uses include routine peroxide monitoring, batch release testing, stability testing and comparative quality assessment.
Related standards
- ISO 212 - Essential oils: Sampling
- ISO 356 - Essential oils: Preparation of test samples
- ISO 3696 - Water for analytical laboratory use (Grade 3)
- (Referenced glassware standard) ISO 385
Keywords: ISO 18321:2015, peroxide value, essential oils, iodometry, potentiometric titration, oxidation testing, peroxide determination, quality control.
Frequently Asked Questions
ISO 18321:2015 is a standard published by the International Organization for Standardization (ISO). Its full title is "Essential oils - Determination of peroxide value". This standard covers: ISO 18321:2015 specifies a method for the determination of the peroxide value in an essential oil. The peroxide value is a measure of the oxidation present.
ISO 18321:2015 specifies a method for the determination of the peroxide value in an essential oil. The peroxide value is a measure of the oxidation present.
ISO 18321:2015 is classified under the following ICS (International Classification for Standards) categories: 71.100.60 - Essential oils. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 18321:2015 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 18321
First edition
2015-05-15
Essential oils — Determination of
peroxide value
Huiles essentielles — Détermination de l’indice de peroxyde
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sampling . 2
8 Preparation of test sample . 2
9 Procedure. 2
9.1 Test portion . 2
9.2 Determination . 3
9.3 Automated potentiometric titration . 3
10 Expression of results . 3
10.1 Calculation . 3
10.2 Conversion from mmol/l to meq/kg . 3
11 Precision . 4
11.1 Repeatability . 4
11.2 Reproducibility . 4
Bibliography . 5
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The committee responsible for this document is ISO/TC 54, Essential
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