[8006-44-8].

Packaging and storage— Preserve in well-closed containers.Store at room temperature,and avoid excessive heat and freezing.Protect from moisture.

USP Reference standards á11ñ— USP Candelilla Wax RS.

Identification—

Melting range,Class IIá741ñ: between 68.5and 72.5.

Acid value á401ñ— Accurately weigh about 3g of Candelilla Wax into a 250-mLflask,add 50mLof a mixture of isopropyl alcohol and toluene (5:4),attach the flask to a reflux condenser,and boil gently until the wax is completely dissolved.Examine the solution:no insoluble particles are present.Remove the flask from the condenser,add about 1mLof phenolphthalein TS,and titrate immediately with 0.5Nalcoholic potassium hydroxide VSto a faint,reddish-yellow color.[NOTE—Do not allow the solution to cool;titrate at a warm temperature after refluxing.After the titration,reserve the solution for use in the test for Saponification value.]Calculate the acid value as the number of mg of potassium hydroxide required to neutralize the free acids in 1g of Candelilla Wax:the acid value is between 12and 22.

Saponification value á401ñ— To the solution from the test for Acid value,add 15.0mLof 0.5Nalcoholic potassium hydroxide VS,reflux for 3to 4hours,and titrate the excess alkali with 0.5Nhydrochloric acid VSto a yellow-amber color.Perform a blank determination under the same conditions (see Residual Titrationsunder Titrimetry á541ñ).The saponification value is the summation of the ester value so obtained and the acid value obtained above:it is between 43and 65.

Heavy metals,Method IIá231ñ: 0.002%.

Limit of lead á251ñ— Accurately weigh about 3.3g of Candelilla Wax into a porcelain dish,heat on a hot plate until completely charred,then heat in a muffle furnace at 480for 8hours or overnight,and cool.Cautiously add 5mLof nitric acid,evaporate to dryness on a hot plate,then heat again in the muffle furnace for exactly 15minutes,and cool.Extract the ash with two 10-mLportions of water,filtering each extract into a separator.Leach any insoluble material on the filter with 6mLof Ammonium Citrate Solution,2mLof Hydroxylamine Hydrochloride Solution,and 5mLof water,adding the filtered washings to the separator.Continue as directed for Procedureunder Lead á251ñbeginning with “Add two drops of phenol red TS”,and use 10mLof Diluted Standard Lead Solutionfor a control containing a total of 10µg of lead:the color of the sample solution does not exceed that in the control (3µg per g).

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 2971

Phone Number:1-301-816-8251