A:Infrared Absorption á197Fñ— 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 solutioncorrespond to those in the chromatogram of the System suitability solution,as obtained in the Content of palmitic acid test.

System suitability solution— Transfer accurately weighed quantities of about 20mg each of cetyl alcohol,stearic acid,palmitic acid,and oleic acid to a 25-mLconical flask fitted with a suitable water-cooled reflux condenser and a magnetic stir bar,and proceed as directed for Test Solutionin Fatty Acid Compositionunder Fats and Fixed Oils á401ñ,beginning with “Add 5.0mLof a solution prepared by dissolving.”

Test solution— Proceed as directed for Test Solutionin Fatty Acid Compositionunder Fats and Fixed Oils á401ñ.

Chromatographic system (see Chromatography á621ñ)— Prepare as directed for Fatty Acid Compositionunder Fats and Fixed Oils á401ñ.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.87for methyl palmitate,0.96for cetyl alcohol,0.99for methyl stearate,and 1.0for 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 1µLof the Test solutioninto the chromatograph,record the chromatogram,identify the methyl palmitate peak in the chromatogram obtained from the Test solutionby 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: in which Ais the peak area of methyl palmitate;and Bis 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.