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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CAS RN^®: 8007-70-3.

1 DEFINITION

Anise Oil is the volatile oil distilled with steam from the dried, ripe fruit of Pimpinella ansium L. (Family Apiaceae). It contains NLT 87% and NMT 94% of trans-anethole. [NOTE-If solid material has separated, carefully warm the Anise Oil until it is completely liquefied, and mix before using.]

2 IDENTIFICATION

Change to read:

2.1 A. CHROMATOGRAPHIC IDENTITY

Peak identification and sensitivity solution: 60 mg/mL of USP Anethole RS, 3 mg/mL of USP Pseudoisoeugenyl 2-methylbutyrate RS, and 0.1 mg/mL each of USP Foeniculin RS and USP Safrole RS in n-hexane

Standard: USP Anise Oil RS

Sample: Anise Oil

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.25 - mm * 30 - m ; coated with 0.25-µm film 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 foeniculin 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 Anise Oil taken:

Result = (r_U/r_T) x 100

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

r_T = sum of all the peak areas from the Sample, 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 Anise Oil RSA (ERR 1-Nov-2020) being used.]

Safrole: NMT 0.01%

Foeniculin: NMT 0.01% [NOTE-In case of a failing result, confirm the presence of foeniculin by GC-MS using the Chromatographic system parameters specified in this test. An interfering peak eluting at or near the retention time of foeniculin may be myristicin. Mass to charge values for molecular and major fragment ions of foeniculin and myristicin obtained with Electron lonization (El) and Chemical lonization (CI) are presented in Table 2. When the absence of foeniculin is confirmed then the Sample meets the acceptance criteria.]

Table 2

Pseudoisoeugenyl 2-methylbutyrate: NLT 0.30%

2.2 B. REFRACTIVE INDEX

Meets the requirements for Refractive Index in Specific Tests

3 ASSAY

3.1 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 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 from the Sample, excluding the solvent peak

Acceptance criteria: 87%-94%

4 IMPURITIES

4.1 LIMIT OF PHENOLS

Sample solution: Recently distilled 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): 1.553-1.560 at 20°

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

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

6.2 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.

6.3 USP REFERENCE STANDARDS (11)

USP Anethole RS

USP Anise Oil RS

USP Foeniculin RS

USP Pseudoisoeugenyl 2-methylbutyrate RS

USP Safrole RS