Phenoxyethanol

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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C₈H₁₀O₂ 138.16

2-Phenoxyethanol;

2-Phenoxyethyl alcohol;

Ethylene glycol, 2-monophenyl ether CAS RN®: 122-99-6.

1 DEFINITION

Phenoxyethanol contains NLT 98.0% and NMT 102.0% of phenoxyethanol (C₈H₁₀O₂).

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F. (CN 1-May-2020) On an undried specimen

3 ASSAY

3.1 Procedure

Phenol solution, Standard solution, and Chromatographic system: Prepare as directed in the test for Organic Impurities.

Sample stock solution: 5 mg/mL of Phenoxyethanol in isopropyl alcohol

Sample solution: Transfer 500 μL of the Sample stock solution to a vial, add 1000 μL of isopropyl alcohol, crimp the vial, and mix on a vortex mixer for 15 s.

3.2 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of phenoxyethanol (C₈H₁₀O₂) in the portion of Phenoxyethanol taken:

Result = (r_U/r_S ) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Phenoxyethanol RS in the Standard solution (mg/mL)

C_U = concentration of Phenoxyethanol in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0%

4 IMPURITIES

Organic Impurities

Phenol solution: 0.25 mg/mL of phenol in isopropyl alcohol

Standard stock solution: 5 mg/mL of USP Phenoxyethanol RS in the Phenol solution

Standard solution: Transfer 500 μL of the Standard stock solution to a vial, add 1000 μL of isopropyl alcohol, crimp the vial, and mix on a vortex mixer for 15 s.

Sample solution: Transfer 500 μL of Phenoxyethanol to a tared vial, and determine the weight of Phenoxyethanol taken. Add 1000 μL of isopropyl alcohol, crimp the vial, and mix on a vortex mixer for 15 s.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.32-mm × 10-m capillary coated with a 5-μm film of stationary phase G27

Temperatures

Injection port: 300°

Detector: 300°

Column: See Table 1.

Table 1

Carrier gas: Helium

Injection volume: 1 μL

Injection type: Split injection mode

Split flow rate: 44 mL/min

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 10 between the phenol and phenoxyethanol peaks

Relative standard deviation: NMT 2.0% for the phenoxyethanol peak

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of total impurities in the portion of Phenoxyethanol taken:

Result = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response of all additional peak areas in the Sample solution, excluding the main peak, the solvent peak, and the phenol peak

r_S = peak response of phenoxyethanol from the Standard solution

C_S = concentration of phenoxyethanol in the Standard solution (mg/mL)

C_U = concentration of the Sample solution (mg/mL)

Acceptance criteria: NMT 1.0%

Limit of Phenol

Phenol solution, Standard solution, Sample solution, and Chromatographic system: Proceed as directed in the test for Organic Impurities.

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of phenol in the portion of Phenoxyethanol taken:

Result = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response of phenol from the Sample solution

r_S = peak response of phenol from the Standard solution

C_S = concentration of phenol in the Standard solution (mg/mL)

C_U = concentration of the Sample solution (mg/mL)

Acceptance criteria: NMT 0.1%

5 SPECIFIC TESTS

Specific Gravity 〈841〉: 1.105–1.110 at 20°

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, and store in a cool, dry place, protected from light.

USP Reference Standards 〈11〉

USP Phenoxyethanol RS