Packaging and storage— Preserve in well-closed containers,preferably in a cold place.

Labeling— Label it to indicate whether it is bleached or is orange,and whether it is dewaxed or wax-containing.

Identification— To 50mg of Shellac add a few drops of a mixture of 1g of ammonium molybdate and 3mLof sulfuric acid:a green color is produced,and it becomes lilac on standing for 5minutes.

Acid value— Dissolve about 2g of finely ground Shellac,accurately weighed,in 50mLof alcohol that has been neutralized to phenolphthalein with 0.1Nsodium hydroxide,add additional phenolphthalein TS,if necessary,and titrate with 0.1Nsodium hydroxide VSto a pink endpoint.[NOTE—For orange Shellac,titrate slowly,stirring vigorously,until a glass rod dipped into the titrated solution produces a color change when touched to a drop of thymol blue TSon a spot plate.]Express the acid value in terms of the number of mg of potassium hydroxide required per g of dried Shellac.

Loss on drying á731ñ— Dry it at 41±2,in a well-ventilated oven,for 24hours.

Heavy metals,Method IIá231ñ: 0.001%.

Wax— Transfer about 10g of finely ground Shellac,accurately weighed,and 2.50g of sodium carbonate to a 200-mL,tall-form beaker.Add 150mLof hot water,immerse the beaker in a boiling water bath,and stir until the solid is dissolved.Cover the beaker with a watch glass,and maintain the heat for 3hours more,without agitation.Remove the beaker to a cold water bath.When the wax has floated to the surface,pass the solution through medium-speed quantitative ashless filter paper,transferring the wax to the paper,and wash the filter with water.Pour 5to 10mLof alcohol onto the filter to facilitate drying.Wrap the paper loosely in a larger piece of filter paper,bind with a piece of fine wire,and dry with the aid of gentle heat.Extract with chloroform in a suitable continuous extraction apparatus for 2hours,using a weighed flask to receive the extracted wax and solvent.Evaporate the solvent,and dry the wax at 105to constant weight.

Rosin— Dissolve 2g by shaking with 10mLof dehydrated alcohol,add slowly,with shaking,50mLof solvent hexane,wash with two successive 50-mLportions of water,filter the washed alcohol–solvent hexane solution,and evaporate to dryness.To the residue add 2mLof a mixture of 1volume of liquefied phenol,½volume of dehydrated alcohol,and 2volumes of solvent hexane.Stir,and transfer a portion of the solution to a cavity of a color-reaction plate.Fill an adjacent cavity with a mixture of 1volume of bromine and 4volumes of solvent hexane,and cover both cavities with an inverted watch glass:no purple or deep indigo-blue color is produced in or above the liquid containing the residue.

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 3072

Phone Number:1-301-816-8330