Hydroxyl value 401
Place about 2 g, accurately weighed, in a dry, glass-stoppered, 250-mL flask, and add 2 mL of pyridine, followed by 10 mL of toluene. To the mixture add 10.0 mL of a solution of acetyl chloride, prepared by mixing 10 mL of acetyl chloride with 90 mL of toluene. Insert the stopper in the flask, and immerse in a water bath heated at 60
to 65
for 20 minutes. Add 25 mL of water, again insert the stopper in the flask, and shake vigorously for several minutes to decompose the excess acetyl chloride. Add 0.5 mL of phenolphthalein TS, and titrate to a permanent pink endpoint with 1 N sodium hydroxide VS, shaking the flask vigorously toward the end of the titration to maintain the contents in an emulsified condition. Perform a blank test with the same quantities of the same reagents and in the same manner. The difference between the number of mL of 1 N sodium hydroxide consumed in the test with the sample and that consumed in the blank test, multiplied by 56.1, and the result divided by the weight, in g, of the Myristyl Alcohol used, represents the hydroxyl value of the Myristyl Alcohol, which is between 250 and 267.
Assay
System suitability solution
Dissolve accurately weighed quantities of USP Myristyl Alcohol RS and
USP Cetyl Alcohol RS in alcohol to obtain a solution containing about 9 mg per mL and 1 mg per mL, respectively.
Assay preparation
Dissolve 100 mg of Myristyl Alcohol in 10.0 mL of dehydrated alcohol, and mix.
Chromatographic system (see Chromatography 621)
The gas chromatograph is equipped with a flame-ionization detector and a 3-mm × 2-m column packed with 10% liquid phase G2 on support S1A. The carrier gas is helium. The column temperature is maintained at about 205
and the injection port and detector temperatures are maintained at about 275
and 250
, respectively. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the resolution,
R, between cetyl alcohol and myristyl alcohol is not less than 4.0; and the relative standard deviation for replicate injections is not more than 1.5%.
Procedure
Inject about 2 µL of the
Assay preparation into the chromatograph, record the chromatogram, and measure the areas for the major peaks. Calculate the percentage of C
14H
30O in the portion of Myristyl Alcohol taken by the formula:
100(rU / rs),
in which
rU is the peak area for myristyl alcohol obtained from the
Assay preparation; and
rs is the sum of the areas of all the peaks except the solvent peak.