Soybean Oil
»Soybean Oil is the refined fixed oil obtained from the seeds of the soya plant Glycine max Merr.(Fabaceae).
Packaging and storage— Preserve in tight,light-resistant containers,and avoid exposure to excessive heat.
Specific gravity á841ñ: between 0.916and 0.922.
Refractive index á831ñ: between 1.465and 1.475.
Free fatty acids á401ñ— The free fatty acids in 10g require for neutralization not more than 2.5mLof 0.020Nsodium hydroxide.
Fatty acid composition— Place about 1g of Oil in a small conical flask fitted with a reflux attachment.Add 10mLof methanol and 0.5mLof 1Nmethanolic potassium hydroxide solution prepared by dissolving 34g of potassium hydroxide in sufficient methanol to produce 500mL,allowing to settle for 24hours,and decanting the clear solution.Reflux the mixture for 10minutes,cool,transfer to a separator with the aid of 15mLof n-heptane,shake with 10mLof saturated sodium chloride solution,and allow to separate.Transfer the lower layer to another separator,and shake it with 10mLof n-heptane.Wash the combined organic layers with 10mLof water,dry over anhydrous sodium sulfate,and filter.Introduce a suitable portion of the filtrate into a gas chromatograph equipped with a flame-ionization detector and a column,preferably glass,1.5m in length and 4mm in internal diameter packed with 10percent liquid phase G4on support S1A,maintained at a temperature of 175.The carrier gas is nitrogen.Measure the 5main peak areas of the methyl esters of the fatty acids.The order of elution is palmitate,stearate,oleate,linoleate,and linolenate,and their relative areas,expressed as percentages of the total area of the 5main peaks,are in the ranges 7to 14,1to 6,19to 30,44to 62,and 4to 11,respectively.
Iodine value,Method IIá401ñ: between 120and 141.
Saponification value á401ñ: between 180and 200.
Unsaponifiable matter á401ñ: not more than 1.0%.
Cottonseed oil— Mix 10mLin a 250-×25-mm test tube with 10mLof a mixture of equal volumes of amyl alcohol and a 1in 100solution of sulfur in carbon disulfide.Warm the mixture carefully.[Caution—Carbon disulfide vapors may be ignited with a hot bath or hot steam pipe. ]When the carbon disulfide has been expelled,immerse the tube to one-third of its length in a boiling,saturated solution of sodium chloride:no red color develops in the mixture within 15minutes.
Peroxide—
Mixed solvent— Mix 60mLof glacial acetic acid with 40mLof chloroform.
Potassium iodide solution— Prepare a saturated solution of potassium iodide in freshly boiled and cooled water,and store it protected from light.Discard it if it gives a color on addition of Mixed solventand starch TS.
Procedure— Transfer about 10g of Oil,accurately weighed,to a conical flask,add 30mLof Mixed solvent,swirl to dissolve,add 0.5mLof Potassium iodide solution,swirl the flask for 1minute,accurately timed,add 30mLof water,and titrate with 0.01Nsodium thiosulfate VS,with vigorous agitation,to a light yellow color.Add 0.5mLof starch TS,and continue the titration until the blue color has disappeared.Perform a blank test,and make any necessary correction.Calculate the peroxide content,in mEq per kg,taken by the formula:
1000VN/W,
in which Vis the volume,in mL,of sodium thiosulfate required and Nis its normality;and Wis the weight,in g,of Oil taken.The limit is 10.0.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 1798
Pharmacopeial Forum:Volume No.30(5)Page 1648
Phone Number:1-301-816-8262