Corn Oil
» Corn Oil is the refined fixed oil obtained from the embryo of Zea mays Linné (Fam. Gramineae).
Packaging and storage— Preserve in tight, light-resistant containers, and avoid exposure to excessive heat.
Specific gravity 841: between 0.914 and 0.921.
Cottonseed oil— Mix 5 mL in a test tube with 5 mL of a mixture of equal volumes of amyl alcohol and a 1 in 100 solution of sulfur in carbon disulfide. Warm the mixture gently until the carbon disulfide is expelled, then immerse the tube to one-third of its depth in a boiling, saturated solution of sodium chloride: no reddish color develops within 15 minutes.
Fatty acid composition— Place about 1 g of Corn 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, allow it to settle for 24 hours, and decant 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 4-mm × 1.8-m column, preferably glass, packed with 10% liquid phase G4 on support S1A, maintained at a temperature of 175. The carrier gas is nitrogen. Measure the five 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 8 to 19, 1 to 4, 19 to 50, 34 to 62, and 1 to 2, respectively.
Free fatty acids 401 The free fatty acids in 10.0 g require for neutralization not more than 2.0 mL of 0.020 N sodium hydroxide.
Iodine value 401: between 102 and 130.
Saponification value 401: between 187 and 193.
Unsaponifiable matter 401: not more than 1.5%.
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 1210
Pharmacopeial Forum: Volume No. 34(5) Page 1220
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.