» Cetyl Palmitate consists of esters of cetyl alcohol and saturated high molecular weight fatty acids, principally palmitic acid.
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.
A: Infrared Absorption 197FUse a thin film of melted test specimen.
B: The retention times of the peaks corresponding to cetyl alcohol and palmitic acid in the chromatogram of the Test solution correspond to those in the chromatogram of the System suitability solution, as obtained in the Content of palmitic acid test.
Melting range, Class II 741: between 46 and 53.
Acid value 401: not more than 1.
Hydroxyl value 401: not more than 6.
Iodine value 401: not more than 1.
Saponification value 401: between 110 and 130.
Loss on drying 731 Dry it at 105 for 1 hour: it loses not more than 3.0% of its weight.
Residue on ignition 281: not more than 0.05%.
Heavy metals, Method II 231: 0.002%.
Content of palmitic acid
System suitability solution Transfer accurately weighed quantities of about 20 mg each of cetyl alcohol, stearic acid, palmitic acid, and oleic acid to a 25-mL conical flask fitted with a suitable water-cooled reflux condenser and a magnetic stir bar, and proceed as directed for Test Solution in Fatty Acid Composition under Fats and Fixed Oils 401, beginning with Add 5.0 mL of a solution prepared by dissolving.
Test solution Proceed as directed for Test Solution in Fatty Acid Composition under Fats and Fixed Oils 401.
Chromatographic system (see Chromatography 621) Prepare as directed for Fatty Acid Composition under Fats and Fixed Oils 401. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.87 for methyl palmitate, 0.96 for cetyl alcohol, 0.99 for methyl stearate, and 1.0 for methyl oleate; the resolution, R, between methyl stearate and methyl oleate is not less than 1.5; the relative standard deviation for the palmitate and stearate peaks for replicate injections is not more than 6.0%; and the relative standard deviation for the response ratio of the palmitate peak to that of stearate for replicate injections is not more than 2.0%.
Procedure Inject about 1 µL of the Test solution into the chromatograph, record the chromatogram, identify the methyl palmitate peak in the chromatogram obtained from the Test solution by comparing the retention times of the peaks in that chromatogram with those in the chromatogram obtained from the System suitability solution, and measure the areas for all of the peaks excluding the solvent peak. Calculate the percentage of palmitic acid in the portion of Cetyl Palmitate taken by the formula:
100(A/B)in which A is the peak area of methyl palmitate; and B is the sum of the areas for all of the peaks, excluding the solvent and cetyl alcohol peaks. The palmitate peak comprises not less than 90% of the total area for all peaks.
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USP32NF27 Page 1204Pharmacopeial Forum: Volume No. 27(1) Page 1825