Soybean Oil
» Soybean Oil is the refined fixed oil obtained from the seeds of the soya plant Glycine max Merr. (Fabaceae). It may contain suitable antioxidants.
Packaging and storage— Preserve in tight, light-resistant containers, and avoid exposure to excessive heat.
Labeling— Label it to indicate the name and quantity of any added antioxidant.
Specific gravity 841: between 0.916 and 0.922.
Refractive index 831: between 1.465 and 1.475.
Free fatty acids 401 The free fatty acids in 10 g require for neutralization not more than 2.5 mL of 0.020 N sodium hydroxide.
Fatty acid composition— Place about 1 g of Oil in a small conical flask fitted with a reflux attachment. Add 10 mL of methanol and 0.5 mL of 1 N methanolic potassium hydroxide solution prepared by dissolving 34 g of potassium hydroxide in sufficient methanol to produce 500 mL, allowing to settle for 24 hours, and decanting the clear solution. Reflux the mixture for 10 minutes, cool, transfer to a separator with the aid of 15 mL of n-heptane, shake with 10 mL of saturated sodium chloride solution, and allow to separate. Transfer the lower layer to another separator, and shake it with 10 mL of n-heptane. Wash the combined organic layers with 10 mL of 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, 1.5 m in length and 4 mm in internal diameter packed with 10% liquid phase G4 on support S1A, maintained at a temperature of 175. The carrier gas is nitrogen. Measure the 5 main 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 5 main peaks, are in the ranges 7 to 14, 1 to 6, 19 to 30, 44 to 62, and 4 to 11, respectively.
Iodine value, Method II 401: between 120 and 141.
Saponification value 401: between 180 and 200.
Unsaponifiable matter 401: not more than 1.0%.
Cottonseed oil— Mix 10 mL in a 250- × 25-mm test tube with 10 mL of a mixture of equal volumes of amyl alcohol and a 1 in 100 solution 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 15 minutes.
Mixed solvent— Mix 60 mL of glacial acetic acid with 40 mL of 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 solvent and starch TS.
Procedure— Transfer about 10 g of Oil, accurately weighed, to a conical flask, add 30 mL of Mixed solvent, swirl to dissolve, add 0.5 mL of Potassium iodide solution, swirl the flask for 1 minute, accurately timed, add 30 mL of water, and titrate with 0.01 N sodium thiosulfate VS, with vigorous agitation, to a light yellow color. Add 0.5 mL of 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:
in which V is the volume, in mL, of sodium thiosulfate required and N is its normality; and W is the weight, in g, of Oil taken. The limit is 10.0.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Hong Wang, Ph.D.
(EM205) Excipient Monographs 2
USP32–NF27 Page 3591
Pharmacopeial Forum: Volume No. 34(4) Page 989
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.