Packaging and storage—
Preserve in tight, light-resistant containers, and prevent exposure to excessive heat.
Labeling—
Label it to indicate the name and quantity of any added antioxidant.
Identification—
The peak responses for the eight major triglycerides, LLL, OLL, PLL, OOL, POL, OOO, SOL, and POO, elute between 0 and about 40 minutes, in the order specified, and at relative retention times of about 0.55, 0.65, 0.69, 0.77, 0.82, 0.93, 0.97, and 1.0, respectively, as obtained in the chromatogram of the Test solution in the test for Triglyceride composition.
Free fatty acids 
401
—
The free fatty acids in 10 g require for neutralization not more than 2.0 mL of 0.020 N sodium hydroxide.
Triglyceride composition—
Mobile phase—
Prepare a filtered and degassed mixture of acetonitrile and methylene chloride (60:40). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
NOTE—The fatty acid radicals are designated as linoleic (L), oleic (O), palmitic (P), and stearic (S), and the common abbreviations for triglycerides used are as follows: trilinolein (LLL), 1,2-dilinoleoyl-3-oleoyl-rac-glycerol (OLL), 1,2-dilinoleoyl-3-palmitoyl-rac-glycerol (PLL), 1,2-dioleoyl-3-linoleoyl-rac-glycerol (OOL), 1-palmitoyl-2-oleoyl-3-linoleoyl-rac-glycerol (POL), triolein (OOO), 1-linoleoyl-2-oleoyl-3-stearoyl-rac-glycerol (SOL), and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (POO).
System suitability solution—
Transfer about 30 mg each of OLL and PLL, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Test solution—
Transfer about 200 mg of Oil, accurately weighed, to a 10-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system
(see
Chromatography 621)—The chromatograph is equipped with a refractive index detector and two 4.6-mm × 25-cm columns in series that contain packings L1 and are maintained at a constant temperature about 30
. The flow rate is about 1.0 mL per minute. Chromatograph the
System suitability solution, and record the peak areas as directed for
Procedure: the relative retention times are about 0.93 for OLL and 1.0 for PLL; the resolution,
R, between OLL and PLL is not less than 1.8; the relative standard deviation for replicate injections, determined from peak areas, is not more than 1.5%; and the relative standard deviation for replicate injections, determined from peak area ratios of OLL to PLL, is not more than 2.2%.
Procedure—
Inject about 20 µL of the
Test solution into the chromatograph, record the chromatogram, and measure the areas for the eight major triglyceride peaks, eluting from 0 to about 40 minutes, with relative retention times stated in the table below and in the order specified. Calculate the percentage of each of these triglycerides in the portion of Oil taken by the formula:
100(A / B),
in which
A is the peak area for each individual triglyceride; and
B is the sum of the areas of all the peaks, excluding the solvent peak.
| Triglyceride |
Relative Retention Time |
Composition (%) |
| LLL |
0.55 |
7.0 to 19.0 |
| OLL |
0.65 |
13.0 to 30.0 |
| PLL |
0.69 |
5.0 to 9.0 |
| OOL |
0.77 |
14.0 to 25.0 |
| POL |
0.82 |
8.0 to 16.0 |
| OOO |
0.93 |
5.0 to 14.0 |
| SOL |
0.97 |
2.0 to 8.0 |
| POO |
1.0 |
2.0 to 8.0 |
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 carefully until the carbon disulfide is expelled, and immerse the tube to one-third of its depth in a boiling saturated solution of sodium chloride: no reddish color develops within 15 minutes.
