Sunflower Oil
(sun'' flow er oyl).
Sunflower Oil is a refined fixed oil obtained from the seeds of the sunflower plant Helianthus annuus Linnè (Fam. Asteraceae alt. Compositae).
•  Heavy Metals, Method II 231: NMT 10 ppm
•  Fats and Fixed Oils, Acid Value (Free Fatty Acids) 401: NMT 2.5 mL of 0.020 N sodium hydroxide is required for neutralization.
•  Fats and Fixed Oils, Fatty Acid Composition 401
Standard solution:  Prepare an ester mixture containing methyl linoleate, methyl oleate, methyl palmitate, methyl stearate, and methyl linolenate (50:35:7:5:3).1
Sample solution:  Transfer 100 mg of Sunflower Oil to a 50-mL conical flask fitted with a suitable water-cooled reflux condenser and a magnetic stir bar. Add 4 mL of 0.5 N methanolic sodium hydroxide solution, and reflux until fat globules disappear (usually 5–10 min). Add 5 mL of a solution prepared by dissolving 14 g of boron trifluoride in methanol to make 100 mL, swirl to mix, and reflux for 2 min. Add 4 mL of chromatographic n-heptane through the condenser, and reflux for 1 min. Cool, remove the condenser, add 15 mL of saturated sodium chloride solution, shake, and allow the layers to separate. Pass the n-heptane layer through 0.1 g of anhydrous sodium sulfate (previously washed with chromatographic n-heptane) into a suitable flask. Transfer 1.0 mL of this solution to a 10-mL volumetric flask, dilute with chromatographic n-heptane to volume, and mix.
Chromatographic system 
Mode:  GC
Detector:  Flame ionization
Column:  0.25-mm × 30-m fused-silica capillary column bonded with a 0.25-µm layer of phase G5
Injector:  220
Detector:  250
Column:  See Table 1.
Table 1
Hold Time
at Final Temperature
120 120 2
120 4 240 5
Carrier gas:  Hydrogen
Flow rate:  1 mL/min
Injection size:  1 µL
Injection type:  Splitless
System suitability 
Sample:  Standard solution
[Note—The relative retention times for methyl palmitate, methyl stearate, and methyl oleate are about 0.87, 0.99, and 1.0, respectively. ]
Suitability requirements 
Resolution:  NLT 1.5 between methyl stearate and methyl oleate
Relative standard deviation:  NMT 6.0% peak area responses for the palmitate and stearate peaks for replicate injections; NMT 1.0% peak area response ratio of the palmitate to stearate peaks from these replicate injections
Samples:  Standard solution and Sample solution
Measure the areas of the five major peaks for the methyl esters of the fatty acids, which elute in the following order: palmitate, stearate, oleate, linoleate, and linolenate.
Calculate the percentage of palmitate, stearate, oleate, linoleate, and linolenate in the portion of Sunflower Oil taken:
Result = (A/B) × 100
A== peak area of palmitate, stearate, oleate, linoleate, or linolenate
B== total area of the five major peaks
Acceptance criteria:  See Table 2.
Table 2
  Generic Oil
Mid-Oleic Oil
High-Oleic Oil
Methyl palmitate 3–10 2–9 2–9
Methyl stearate 2–8 2–8 2–8
Methyl oleate 14–24 40–70 70–90
Methyl linoleate 63–73 15–40 5–15
Methyl linolenate 0–3 0–3 0–3
•  Fats and Fixed Oils, Iodine Value, Method II 401
Acceptance criteria 
Generic oil:  128–148
Mid-oleic oil:  98–118
High-oleic oil:  78–98
•  Limit of Peroxide
[Note—This test must be performed promptly after sampling to avoid oxidation of the test specimen. ]
Solvent A:  Chloroform and glacial acetic acid (40:60)
Potassium iodide solution:  Prepare a saturated solution of potassium iodide in freshly boiled and cooled water, and store protected from light. [Note—Discard the solution if it becomes colored upon addition of Solvent A and iodine-free starch TS. ]
Sample:  10 g of Sunflower Oil
Analysis:  Transfer the Sample to a conical flask, add 30 mL of Solvent A, and swirl to dissolve. Add 0.5 mL of Potassium iodide solution, swirl for 1.0 min, and add 30 mL of water. Titrate with 0.01 N sodium thiosulfate VS, with vigorous agitation, to a light yellow color. Add 2.0 mL of iodine-free starch TS, and continue the titration until the blue color has disappeared. Perform a blank determination, and make any necessary correction.
Calculate the amount of peroxide, in mEq/kg, in the portion of Sunflower Oil taken:
Result = (V × N/W) × F
V== volume of sodium thiosulfate used in the titration (mL)
N== normality of sodium thiosulfate VS (mEq/mL)
W== weight of Sunflower Oil taken (g)
F== conversion factor, 1000 g/kg
Acceptance criteria:  NMT 10.0 mEq/kg
•  Refractive Index 831: 1.472–1.474 at 20
•  Specific Gravity 841: 0.914–0.924 at 20
•  Packaging and Storage: Preserve in tight, light-resistant containers. No storage requirement specified.
•  Labeling: The label states the Latin binomial and, following the official name, the part of the plant source from which the article was derived. The label also indicates the name and concentration of any additive.

1  Ester mixtures are available commercially from Nu-Chek-Prep, Inc., P.O. Box 295, Elysian, MN 56028. Typical Nu-Chek-Prep ester mixtures useful in this test include Nu-Chek 15A. This mixture may contain other components.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
USP35–NF30 Page 2001
Pharmacopeial Forum: Volume No. 31(1) Page 95