Eucalyptol

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1,3,3-Trimethyl-2-oxabicyclo[2.2.2]octane;

1,8-Epoxy-p-menthane CAS RN®: 470-82-6; UNII: RV6J6604TK.

1 DEFINITION

Eucalyptol is obtained from oil of eucalyptus and from other sources. It contains NLT 98.0% and NMT 100.0% of C₁₀H₁₈O.

2 IDENTIFICATION

Change to read:

A.SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197E (CN 1-Mar-2020)

B. Add 1 mL of phosphoric acid to 1 ml of Eucalyptol contained in a test tube maintained in an ice bath. A solid white crystalline mass is formed, from which eucalyptol separates upon addition of warm water.

3 ASSAY

PROCEDURE

System suitability solution: 0.2 mg/ml of Limonene and 0.9 mg/mL of USP Eucalyptol RS in methanol

Sample solution: 0.9 mg/mL of Eucalyptol in methanol

Blank: Methanol

Chromatographic system

(See Chromatography (621) System Suitability.)

Mode: GC

OFFICIAL

Detector: Flame ionization

Column: 0.32-mm x 60-m fused-silica capillary column coated with phase G16

Temperature

Injector port: 250°

Detector: 250°

Column: See Table 1.

Split flow rate: 50 mL/min

Carrier gas: Helium

Column head pressure: 30 psi

Injection size: 1 µL

System suitability

Sample: System suitability solution

Suitability requirements

Resolution: NLT 2.0 between limonene and eucalyptol

Column efficiency: NLT 150,000 theoretical plates, eucalyptol

Analysis

Samples: Sample solution and Blank

[Nore-identify any peaks from the Sample solution that correspond to those in the Blank by their retention times.) Calculate the percentage of eucalyptol (C,H,O) in the portion of Eucalyptol taken:

Result = (r_U/(r_S) x 100

r_U = peak response of eucalyptol from the Sample solution

r_S = sum of all peak resporises from the Sample solution, other than the responses corresponding to those of the Blank

Acceptance criteria: 98.0%-100.0%

4 IMPURITIES

LIMIT OF PHENOLS

Analysis 1: Shake 5 ml, with 5 ml. of sodium hydroxide TS.

Acceptance criteria 1: The volume of Eucalyptol is not diminished.

Analysis 2: Shake 1 ml with 20 ml of water and allow the liquids to separate. To 10 ml of the water layer add 1 drop of ferric chloride TS.

Acceptance criteria 2: The mixture develops no violet color.

5 SPECIFIC TESTS

• Specific Gravity (841): 0.921–0.924

• Congealing Temperature (651): NLT 0°

• Optical Rotation, Angular Rotation (781A): −0.5° to +0.5°

• Distilling Range, Method I (721): 174°–177°

• Refractive Index (831): 1.455–1.460 at 20°

ADDITIONAL REQUIREMENTS

• Packaging and Storage: Preserve in tight containers.