Star Anise Oil

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 DEFINITION

Star Anise Oil is the volatile oil distilled with steam from the dried, ripe fruit of Illicium verum Hook. f. It contains NLT 86% and NMT 93% of trans-anethole.

[Note—If solid material has separated, carefully warm the Star Anise Oil until it is completely liqufied, and mix before using.]

2 IDENTIFICATION

A. Chromatographic Identity

Peak identi

cation and sensitivity solution: 60 mg/mL of USP Anethole RS, 1 mg/mL of USP Foeniculin RS, and 0.1 mg/mL each of USP

Pseudoisoeugenyl 2-methylbutyrate RS and USP Safrole RS in n-hexane

Standard: USP Star Anise Oil RS

Sample: Star Anise Oil

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.25-mm × 30-m; coated with a 0.25-μm

lm of phase G16

Temperatures

Injection port: 200°

Detector: 220°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 1.0 mL/min

Injection volume: 0.4 μL

Injection type: Split; split ratio, 100:1

System suitability

Sample: Peak identification and sensitivity solution

[Note—The relative retention times for the trans-anethole, safrole, foeniculin, and pseudoisoeugenyl 2-methylbutyrate peaks are 1.0, 1.04, 1.5, and 1.7, respectively.]

Suitability requirements

Signal-to-noise ratio: NLT 10 for the pseudoisoeugenyl 2-methylbutyrate and safrole peaks

Analysis

Samples: Peak identification and sensitivity solution, Standard, and Sample

Identify the safrole, foeniculin, and pseudoisoeugenyl 2-methylbutyrate peaks in the chromatogram of the Sample based on those in the chromatogram of the Peak identification and sensitivity solution.

Calculate the percentage of safrole, foeniculin, and pseudoisoeugenyl 2-methylbutyrate in the portion of Star Anise Oil taken:

Result = (r_U/r_T) × 100

r_U = peak area of safrole or foeniculin or pseudoisoeugenyl 2-methylbutyrate from the Sample

r_T = sum of all the peak areas, excluding the solvent peak

Acceptance criteria

Chromatographic similarity: Examine the chromatograms of the Sample and the Standard. The chromatogram of the Sample is similar to that of the Standard.[Note—The chromatogram of the Standard is similar to the reference chromatogram provided with the lot of USP Star

Anise Oil RS being used.]

Safrole: NMT 0.01%

Foeniculin: NLT 0.10%

Pseudoisoeugenyl 2-methylbutyrate: NMT 0.01%

B. Refractive Index: Meets the requirements for Refractive Index in Speci

c Tests

3 ASSAY

Content of trans-Anethole

Peak identification and sensitivity solution, Sample, and Chromatographic system: Proceed as directed in Identification A.

Analysis

Samples: Peak identification and sensitivity solution and Sample

Identify the trans-anethole peak in the chromatogram of the Sample based on that in the chromatogram of the Peak identification and sensitivity solution.

Calculate the percentage of trans-anethole in the portion of Star Anise Oil taken:

Result = (r_U/r_T) × 100

r_U = peak area of trans-anethole from the Sample

r_T = sum of all the peak areas, excluding the solvent peak

Acceptance criteria: 86%–93%

4 IMPURITIES

Limit of Phenols

Sample solution: Recently distilled Star Anise Oil in 90% alcohol (1 in 3)

Acceptance criteria: The Sample solution is neutral to moistened neutral litmus paper, and no blue or brownish color develops upon the

addition of 1 drop of ferric chloride TS to 5 mL of the Sample solution.

5 SPECIFIC TESTS

Solubility in 90% Alcohol: 1 volume dissolves in 3 volumes of 90% alcohol.

Refractive Index 〈831〉: 1.553–1.556 at 20°

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-filled, tight containers, and protect from light. Avoid exposure to excessive heat.

Labeling: The label states the Latin binomial name and, following the official name, the part of the plant source from which the article was derived. The label also states that if solid material has separated, carefully warm the oil until it is completely liquefied, and mix before using.

USP Reference Standards 〈11〉

USP Anethole RS

USP Foeniculin RS

USP Pseudoisoeugenyl 2-methylbutyrate RS

USP Safrole RS

USP Star Anise Oil RS (NF 1-Aug-2019)