Sorbitan Monooleate
[Graphic formula same as for Sorbitan Monolaurate,except that Ris (C17H33)COO.]
Sorbitan,esters,mono(Z)-9-octadecenoate.
Sorbitan monooleate [1338-43-8].
»Sorbitan Monooleate is a partial oleate ester of Sorbitol and its mono-and dianhydrides.It yields,upon saponification,not less than 72.0percent and not more than 78.0percent of fatty acids,and not less than 25.0percent and not more than 31.0percent of polyols (w/w).
Packaging and storage—
Preserve in tight containers.
Identification—
A:
The residue of oleic acid obtained in the Assay for fatty acidshas an acid value (see Fats and Fixed Oils á401ñ)between 192and 204,about 1g of the residue,accurately weighed,being used,and an iodine value (see Fats and Fixed Oils á401ñ)between 75and 95.
B:
Standard preparation—Transfer 33mg of USP Isosorbide RS,25mg of USP1,4-Sorbitan RS,and 25mg of sorbitol to a 1-mLvolumetric flask,dilute with water to volume,and mix to dissolve.
Test preparation—
Transfer 500mg of the polyols obtained in the Assay for polyolsto a 2-mLvolumetric flask,dilute with water to volume,and mix to dissolve.
Procedure—
Apply 2µLeach of the Standard preparationand of the Test preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Allow the spots to dry,and develop the chromatogram in a solvent system consisting of a mixture of acetone and glacial acetic acid (50:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate.Spray evenly with a mixture of equal volumes of sulfuric acid and water until the surface is uniformly wet (do not overspray),and immediately place the sprayed plate on a 200
hot plate in a well-ventilated hood.Char until white fumes of sulfur trioxide cease,and cool:the RFvalues of the spots obtained from the Test preparationcorrespond to those of the spots obtained from the Standard preparation.
hot plate in a well-ventilated hood.Char until white fumes of sulfur trioxide cease,and cool:the RFvalues of the spots obtained from the Test preparationcorrespond to those of the spots obtained from the Standard preparation.
Acid value á401ñ:
not more than 8.
Hydroxyl value á401ñ:
between 190and 215.
Iodine value á401ñ:
between 62and 76.
Saponification value á401ñ:
between 145and 160.
Water,Method Iá921ñ:
not more than 1.0%.
Residue on ignition á281ñ:
not more than 0.5%.
Heavy metals,Method IIá231ñ:
0.001%.
Organic volatile impurities,Method IVá467ñ:
meets the requirements.[NOTE—A G16column has been shown to be an appropriate secondary column.]
Assay for fatty acids—
Transfer about 10g of Sorbitan Monooleate,accurately weighed,to a 500-mLconical flask,cautiously add 100mLof alcohol and 3.5g of potassium hydroxide,then add a few glass beads,and mix.Connect a suitable condenser to the flask,reflux the mixture on a hot plate for 2hours,add about 100mLof water,and heat on a steam bath to evaporate the alcohol,adding water occasionally to replace the alcohol.Continue the evaporation until the odor of alcohol can no longer be detected,and transfer the saponification mixture,with the aid of about 100mLof hot water,to a 500-mLseparator.Using extreme caution,neutralize to litmus with a mixture of equal volumes of sulfuric acid and water,noting the volume used,and add a 10%excess of the dilute acid.Allow the solution to cool.If salts appear,add sufficient water to produce a clear solution.Cautiously add 100mLof solvent hexane,shake thoroughly,and withdraw the lower layer into a second 500-mLseparator.Similarly extract with 2more 100-mLportions of solvent hexane.Extract the combined hexane layers with 50-mLportions of water until neutral to litmus paper,and combine the extracts with the original aqueous phase,for the Assay for polyols.Evaporate the solvent hexane in a tared beaker on a steam bath nearly to dryness,dry in vacuum at 60for 1hour,cool in a desiccator,and weigh the fatty acids.
for 1hour,cool in a desiccator,and weigh the fatty acids.
Assay for polyols—
Neutralize the aqueous solution of polyols retained from the Assay for fatty acidswith potassium hydroxide solution (1in 10)to a pHof 7,using a suitable pHmeter.Evaporate on a steam bath to a moist residue,extract the polyols from the salts with three 150-mLportions of dehydrated alcohol,boiling the salt residue for 3minutes,and crushing it,as necessary,with the flattened end of a stirring rod,during each extraction,filtering each extract,while hot,through a medium-porosity,sintered-glass funnel,provided with a sheet of retentive filter paper on which a layer of purified siliceous earth has been superimposed,and receiving the filtrates in a 1-liter suction flask.Transfer the clear alcoholic polyols solution to a tared beaker,evaporate the alcohol on a steam bath,dry in vacuum at 60for 1hour,cool in a desiccator,and weigh the polyols.
for 1hour,cool in a desiccator,and weigh the polyols.
Auxiliary Information—
Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3083
Phone Number:1-301-816-8330