Periodic acid solution— Dissolve 5.4 g of periodic acid in 100 mL of water, and add 1900 mL of glacial acetic acid. Store in a glass-stoppered bottle, protected from light.

Chloroform— Use chloroform that meets the following additional requirement. To each of three glass-stoppered, 500-mL conical flasks add 50.0 mL of Periodic acid solution, then add 50 mL of chloroform and 10 mL of water to two of the flasks and 50 mL of water to the third flask. To each flask add 20 mL of potassium iodide TS, mix gently, and proceed as directed for Procedure, beginning with “allow to stand for 1 to 5 minutes.” The difference between the volumes of 0.1 N sodium thiosulfate required in the titrations with and without the chloroform does not exceed 100 µL.

Procedure— Melt the Propylene Glycol Monostearate at a temperature not above 55, and mix. Transfer a 3-g portion, accurately weighed, to a 100-mL beaker, and dissolve in 25 mL of Chloroform. Transfer this solution, with the aid of another 25-mL portion of Chloroform, to a separator, wash the beaker with 25 mL of water, and add the washing to the separator. Insert the stopper, shake vigorously for 30 to 60 seconds, and allow the layers to separate, adding 1 mL to 2 mL of glacial acetic acid, if necessary, to break any emulsion. Transfer the aqueous layer to a glass-stoppered, 500-mL conical flask, wash the chloroform layer with two 25-mL portions of water, combining the washings with the aqueous layer, and discard the chloroform layer. Add, with swirling, 50.0 mL of Periodic acid solution to the solution and to another glass-stoppered, 500-mL conical flask containing 75 mL of water to provide the blank. Allow to stand for 30 to 90 minutes. To each flask add 20 mL of potassium iodide TS, mix gently, and allow to stand for 1 to 5 minutes before titrating. Add 100 mL of water, and titrate with 0.1 N sodium thiosulfate VS until the brown iodine color fades to pale yellow, add 3 mL of starch TS, and continue the titration to the disappearance of the blue color. Propylene Glycol Monostearate contains not more than 1.0% of free glycerin and propylene glycol, calculated as propylene glycol taken by the formula: in which 3.805 is the molecular weight of propylene glycol divided by 20; N is the exact normality of the sodium thiosulfate solution; B and T are the volumes, in mL, of sodium thiosulfate consumed in the titrations of the blank solution and test solution, respectively; and W is the weight, in g, of Propylene Glycol Monostearate taken.

[M(H F)] / 561.1;

(56,110 / A) + 76.10 18.02;

561.1G / 38.05,

(Official January 1, 2007)