Identification—
A: Infrared Absorption 
197F
—
Use 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.
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.”
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.
;)
for 1 hour: it loses not more than 3.0% of its weight.