Cetyl Palmitate

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
DOWNLOAD PDF HERE

1 DEFINITION

Cetyl Palmitate contains NLT 90.0% and NMT 103.0% of cetyl palmitate (C H O ). It consists of esters of cetyl alcohol and saturated high molecular weight fatty acids, principally palmitic acid.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F

Sample: Use a thin film of melted test specimen.

Acceptance criteria: Meets the requirements

B. Chromatographic Identity

Analysis: Proceed as directed in the Assay.

Acceptance criteria: The retention time of the cetyl palmitate peak from the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Diluent: n-Hexane

System suitability solution: 1 mg/mL of USP Cetyl Esters Wax RS in Diluent

Standard solution: 1 mg/mL of USP Cetyl Palmitate RS in Diluent

Sample solution: 1 mg/mL of Cetyl Palmitate in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.53-mm × 10-m fused-silica capillary; 2.65-μm layer of phase G2

Temperatures

Injector: 350°

Detector: 350°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 6.5 mL/min

Injection volume: 1 μL

Injection type: Split, split ratio 10:1

Run time: 25 min

System suitability

Sample: System suitability solution

[Note—For relative retention times, see Table 2.]

Table 2

Suitability requirements

Resolution: NLT 2.0 between fatty esters with carbon-chain length of carbon number 32 and fatty esters with carbon-chain length of carbon number 34, System suitability solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of cetyl palmitate (fatty esters with carbon-chain length carbon number 32) in the portion of Cetyl Palmitate taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U= peak response of cetyl palmitate from the Sample solution

r_S= peak response of cetyl palmitate from the Standard solution

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

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

Acceptance criteria: 90.0%–103.0%

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.05%

Change to read:

Limit of Fatty Alcohols, Fatty Acids, and Fatty esters

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

System suitability

Sample: System suitability solution

[Note—For relative retention times, see Table 3.]

Table 3

Suitability requirements

Resolution: NLT 2.0 between fatty esters with carbon-chain length of carbon number 32 and fatty esters with carbon-chain length of carbon number 34, System suitability solution

Analysis

Samples: System suitability solution and Sample solution

Identify cetyl alcohol, palmitic acid, and each of the fatty esters in the Sample solution based on those in the System suitability solution

(Table 3).

Calculate the percentage of cetyl alcohol, palmitic acid, and each of the fatty esters in the portion of Cetyl Palmitate taken:

Result = (r_U/r_T) × 100

r_U= peak area of cetyl alcohol, palmitic acid, and each of the fatty esters from the Sample solution

r_T= sum of the total peak areas from the Sample solution, except for the peak areas from solvent

Acceptance criteria: See Table 4.

Table 4

5 SPECIFIC TESTS

Melting Range or Temperature 〈741〉, Procedures, Procedure for Class II: 46°–53°

Fats and Fixed Oils 〈401〉, Procedures, Acid Value: NMT 1

Fats and Fixed Oils 〈401〉, Procedures, Hydroxyl Value: NMT 6

Fats and Fixed Oils 〈401〉, Procedures, Iodine Value: NMT 1

Fats and Fixed Oils 〈401〉, Procedures, Saponification Value: 110–130

Loss on Drying 〈731〉

Analysis: Dry at 105° for 1 h.

Acceptance criteria: NMT 3.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers at controlled room temperature, and avoid exposure to excessive heat.

USP Reference Standards 〈11〉

USP Cetyl Palmitate RS

USP Cetyl Esters Wax RS