Emulsifying Wax
» Emulsifying Wax is a waxy solid prepared from Cetostearyl Alcohol containing a polyoxyethylene derivative of a fatty acid ester of sorbitan.
Packaging and storage— Preserve in well-closed containers.
Melting range 741: between 50 and 54, the following method being used. Melt a quantity of the test substance slowly, while stirring, until it reaches a temperature of 90 to 92, remove the source of the heat, and allow the molten substance to cool to a temperature of 8 to 10 above the expected melting point. Chill the bulb of a suitable thermometer (see Thermometers 21) to 5, wipe it dry, and while it is still cold, dip it into the molten substance so that the bulb is completely covered. Withdraw it immediately, and hold it vertically away from the heat until the surface dulls. Fix the thermometer securely in a test tube so that the lower point is 15 mm from the bottom of the test tube. Place the test tube in a water bath at 10 to 15 and allow it to remain at that temperature for 30 minutes. Raise the temperature of the bath at the rate of 2 per minute to 30, then change to a rate of 1 per minute, and note the temperature at which the first drop of melted substance leaves the thermometer. Repeat the determination twice on a freshly melted portion of the test substance. If the variation of three determinations is less than 1, take the average of the three as the melting point. Otherwise, make two additional determinations, and take the average of the five.
Hydroxyl value 401: between 178 and 192.
Iodine value 401: not more than 3.5.
Saponification value 401: not more than 14.
pH 791: between 5.5 and 7.0, in a dispersion prepared by heating a mixture of 3 g of it in 100 mL of water to 55, with stirring, followed by cooling to 25.
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Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
USP35–NF30 Page 2015