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467
:
meets the requirements.
781S :
not less than +24.0
. [NOTE—This test identifies d-alpha tocopherol after saponification.]
, accurately weighed, to a suitable test tube fitted with a cap, and dissolve in 10.0 mL of alcohol. Place the tube in a heating block set between 100 and 105. [NOTE—Solution is to reflux gently without emission of contents.] When sample is fully dissolved, add 2 to 3 pellets of sodium hydroxide, and continue to reflux for an additional 30 minutes. Remove the tube from the heat and while contents are still hot, neutralize using phenolphthalein as the indicator by slowly adding 10 mL of a mixture of water and hydrochloric acid (1:1) until the pink color disappears. [Caution—Exothermic reaction. Allow the acid solution to trickle down the inside of the tube to prevent splashing.
] Cool the tube, cap, and shake until contents are well mixed. Add 25.0 mL of heptane, cap, and shake for 1 minute to ensure thorough mixing. Allow the tube to stand until two distinct layers are formed. Remove the top layer to a clean dry culture tube, then add 10.0 mL of water to the recovered solution. Cap, shake, and allow layers to separate. Transfer the upper layer to a clean dry tube. Add 10.0 mL of potassium ferricyanide solution, prepared by dissolving 2 g of potassium ferricyanide in 10.0 mL of 0.2 M sodium hydroxide, and replace the cap. Shake vigorously for 45 seconds, and allow the layers to separate for 30 minutes. If the top heptane layer is clear, proceed with the measurement for specific rotation; if not clear, dry over anhydrous sodium sulfate before proceeding with the test. [NOTE—Use the results of the test for Content of alpha tocopherol below to calculate the specific rotation.]
for 10 minutes. Cool the flask, add 5.0 mL of Internal standard solution followed by 20 mL of isooctane, and shake.
to a culture tube (about 20 cm long and 2.5 cm in diameter) with a screw cap. Add 40 to 50 mg of ascorbic acid and a few boiling chips followed by 20 mL of Solvent. Place the tube in a heating block set between 100 and 150. [NOTE—Solution is to reflux gently without emission of contents.] When sample is fully dissolved add 0.25 g of potassium hydroxide and continue to reflux for 30 minutes. Remove the tube from heat and while contents are still hot, add 1 to 2 mL of hydrochloric acid dropwise until the pink coloration disappears. [Caution—Exothermic reaction. Allow the acid to trickle down the inside of the tube to prevent splashing.
] Cool the tube, then wash the sides of the tube with 20 mL of water. Add 5.0 mL of Internal standard solution, cap, and shake to ensure thorough mixing. Allow the tube to stand until two distinct layers are formed. Transfer 2.5 to 3.5 mL of the upper layer into a suitable reaction flask, and add 2.0 mL of pyridine followed by 2.5 mL of N,O-bis(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane. Heat the flask at 100 for 10 minutes. Cool, and then add 12 mL of isooctane.
621)—
The gas chromatograph is equipped with a split injector, a flame-ionization detector, and a 0.25-mm × 15-m fused-silica capillary column coated with a 0.25-µm film of phase G27. The injection port and detector temperatures are maintained at 280 and 345, respectively. The column temperature is programmed to rise at a rate of 20 per minute from 260 at the time of injection to 340, where it is held for 1 minute. The carrier gas is helium flowing at a rate of 1.5 mL per minute, and the split flow is about 300 mL per minute. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the tailing factor for the analyte peak is not more than 2.0; and the relative standard deviation for replicate injections is not more than 2.0% for the ratio of the alpha tocopherol response to the internal standard response.
467:
meets the requirements.