Avobenzone

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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C₂₀H₂₂O₃  310.40

1,3-Propanedione, 1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-;

1-(p-tert-Butylphenyl)-3-(p-methoxyphenyl)-1,3-propanedione CAS RN^®: 70356-09-1; UNII: G63QQF2NOX.

1 DEFINITION

Avobenzone contains NLT 95.0% and NMT 105.0% of avobenzone (C₂₀H₂₂O₃), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K or (197A) (USP 1-Aug-2020)

Change to read:

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. (USP 1-Aug-2020)

3 ASSAY

Change to read:

3.1 PROCEDURE

Standard solution: 50 mg/mL of USP Avobenzone RS in acetone

Sample solution: 50 mg/mL of Avobenzone in acetone

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 2 mL/min (USP 1-Aug-2020)

Injection volume: 1 µL

Injection type: Split, split ratio 50:1

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of avobenzone (C₂₀H₂₂O₃) in the portion of Avobenzone taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of avobenzone from the Sample solution

r_S = peak response of avobenzone from the Standard solution 

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

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

Acceptance criteria: 95.0%-105.0% on the dried basis

4 IMPURITIES

4.1 ORGANIC IMPURITIES

Sample solution, Chromatographic system, and System suitability: Proceed as directed in the Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each individual impurity in the portion of Avobenzone taken:

Result = (r_U/r_T) x 100

r_U = peak response of each individual impurity from the Sample solution

r_T = sum of all the peak responses from the Sample solution

Acceptance criteria

Any unspecified impurity: NMT 3.0%

Total impurities: NMT 4.5%

5 SPECIFIC TESTS

LOSS ON DRYING (731)

Analysis: Dry under vacuum at 70° for 4 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight, light-resistant containers.

USP REFERENCE STANDARDS (11)

USP Avobenzone RS