Triglyceride composition
Mobile phase
Prepare a filtered and degassed mixture of acetonitrile and methylene chloride (60:40).Make adjustments if necessary (see System Suitabilityunder Chromatography).
NOTEThe 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 30mg each of OLLand PLL,accurately weighed,to a 10-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.
Test solution
Transfer about 200mg of Oil,accurately weighed,to a 10-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Chromatographic system
(see
Chromatography á621ñ)The chromatograph is equipped with a refractive index detector and two 4.6-mm ×25-cm columns in series that contain packings L1and are maintained at a constant temperature about 30

.The flow rate is about 1.0mLper minute.Chromatograph the
System suitability solution,and record the peak areas as directed for
Procedure:the relative retention times are about 0.93for OLLand 1.0for PLL;the resolution,
R,between OLLand PLLis 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 OLLto PLL,is not more than 2.2%.
Procedure
Inject about 20µLof the
Test solutioninto the chromatograph,record the chromatogram,and measure the areas for the eight major triglyceride peaks,eluting from 0to about 40minutes,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
Ais the peak area for each individual triglyceride;and
Bis the sum of the areas of all the peaks,excluding the solvent peak.
| Triglyceride |
Relative Retention Time |
Composition (%) |
| LLL |
0.55 |
7.0to 19.0 |
| OLL |
0.65 |
13.0to 30.0 |
| PLL |
0.69 |
5.0to 9.0 |
| OOL |
0.77 |
14.0to 25.0 |
| POL |
0.82 |
8.0to 16.0 |
| OOO |
0.93 |
5.0to 14.0 |
| SOL |
0.97 |
2.0to 8.0 |
| POO |
1.0 |
2.0to 8.0 |