Lecithin
»Lecithin is a complex mixture of acetone-insoluble phosphatides,which consist chiefly of phosphatidyl choline,phosphatidyl ethanolamine,phosphatidyl serine,and phosphatidyl inositol,combined with various amounts of other substances such as triglycerides,fatty acids,and carbohydrates,as separated from the crude vegetable oil source.It contains not less than 50.0percent of acetone-insoluble matter.
Packaging and storage—
Preserve in well-closed containers.
Acid value á401ñ:
If the substance under test is plastic or semisolid,soften the Lecithin by warming it briefly at a temperature not exceeding 60
,and then mix.Transfer about 2g,accurately weighed,to a 250-mLconical flask,and dissolve it in 50mLof solvent hexane.To this solution add 50mLof alcohol,previously neutralized to phenolphthalein with 0.1Nsodium hydroxide,and mix.Add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VSto a pink endpoint that persists for 5seconds.Calculate the number of mg of potassium hydroxide required to neutralize the free acids in 1.0g of the specimen by multiplying the number of mLof 0.1Nsodium hydroxide VSconsumed in the titration by 5.6and dividing the result by the weight,in g,of the test specimen:not more than 36mg of potassium hydroxide are required to neutralize the free acids.
,and then mix.Transfer about 2g,accurately weighed,to a 250-mLconical flask,and dissolve it in 50mLof solvent hexane.To this solution add 50mLof alcohol,previously neutralized to phenolphthalein with 0.1Nsodium hydroxide,and mix.Add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VSto a pink endpoint that persists for 5seconds.Calculate the number of mg of potassium hydroxide required to neutralize the free acids in 1.0g of the specimen by multiplying the number of mLof 0.1Nsodium hydroxide VSconsumed in the titration by 5.6and dividing the result by the weight,in g,of the test specimen:not more than 36mg of potassium hydroxide are required to neutralize the free acids.
Water,Method Iá921ñ:
not more than 1.5%.
Hexane-insoluble matter—
If the substance under test is plastic or semisolid,soften the Lecithin by warming it at a temperature not exceeding 60,and then mix.Weigh 10.0g into a 250-mLconical flask,add 100mLof solvent hexane,and shake until solution is apparently complete or until no more of any residue seems to be dissolving.Filter through a coarse-porosity filtering funnel that previously has been heated at 105for 1hour,cooled,and weighed,wash the flask with two 25-mLportions of solvent hexane,and pour both washings through the funnel.Dry the funnel at 105for 1hour.[Caution—Hexane is flammable.
]Cool to room temperature,and determine the gain in weight:not more than 0.3%is found.
,and then mix.Weigh 10.0g into a 250-mLconical flask,add 100mLof solvent hexane,and shake until solution is apparently complete or until no more of any residue seems to be dissolving.Filter through a coarse-porosity filtering funnel that previously has been heated at 105for 1hour,cooled,and weighed,wash the flask with two 25-mLportions of solvent hexane,and pour both washings through the funnel.Dry the funnel at 105for 1hour.[Caution—Hexane is flammable.
]Cool to room temperature,and determine the gain in weight:not more than 0.3%is found.
Lead á251ñ:
0.001%.
Heavy metals,Method IIá231ñ:
20µg per g.
Organic volatile impurities,Method IVá467ñ:
meets the requirements.
Content of acetone-insoluble matter—
If the substance under test is plastic or semisolid,soften the Lecithin by warming it briefly at a temperature not exceeding 60,and then mix.Transfer about 2g to a 40-mLcentrifuge tube that previously has been tared with a stirring rod,cool,and weigh accurately.Add 15.0mLof acetone,warm carefully in a water bath to melt the test specimen without evaporating the acetone,but with stirring to aid complete disintegration,and place in an ice-water bath for 5minutes.Add acetone that previously has been chilled to 0to 5to the 40-mLmark on the tube,stirring during the addition.Cool in an ice-water bath for 15minutes,stir,remove the rod,clarify by centrifuging at about 2000rpm for 5minutes,and decant.Break up the residue with the stirring rod,and refill the centrifuge tube to the 40-mLmark with chilled acetone,while stirring.Cool in an ice-water bath for 15minutes,stir,remove the rod,centrifuge,and decant.Break up the residue with the stirring rod.Place the tube in a horizontal position until most of the acetone has evaporated,mix again,and heat the tube containing the acetone-insoluble residue and the stirring rod at 105to constant weight.[Caution—Acetone is flammable.
]Determine the weight of the residue,and calculate the percentage of acetone-insoluble matter.
,and then mix.Transfer about 2g to a 40-mLcentrifuge tube that previously has been tared with a stirring rod,cool,and weigh accurately.Add 15.0mLof acetone,warm carefully in a water bath to melt the test specimen without evaporating the acetone,but with stirring to aid complete disintegration,and place in an ice-water bath for 5minutes.Add acetone that previously has been chilled to 0to 5to the 40-mLmark on the tube,stirring during the addition.Cool in an ice-water bath for 15minutes,stir,remove the rod,clarify by centrifuging at about 2000rpm for 5minutes,and decant.Break up the residue with the stirring rod,and refill the centrifuge tube to the 40-mLmark with chilled acetone,while stirring.Cool in an ice-water bath for 15minutes,stir,remove the rod,centrifuge,and decant.Break up the residue with the stirring rod.Place the tube in a horizontal position until most of the acetone has evaporated,mix again,and heat the tube containing the acetone-insoluble residue and the stirring rod at 105to constant weight.[Caution—Acetone is flammable.
]Determine the weight of the residue,and calculate the percentage of acetone-insoluble matter.
Auxiliary Information—
Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3025
Phone Number:1-301-816-8262