Tocopherol
The most commonly used natural antioxidant for foodstuffs, pharmaceuticals and cosmetics. Natural tocopherols are obtained as an ancillary product in the production of vegetable oils. They are relatively mild compounds, suitable for use in food products, cosmetics, and those vegetable oils which have low tocopherol c
Tocopherol
C29H50O2
Formula wt 430.71
INS: 307
CAS: [2074-53-5]Natural Mixture of alpha, beta, gamma and delta tocopherols
Description
A form of vitamin E. It occurs as a yellow to amber, nearly odorless, clear, viscous oil that oxidizes and darkens in air and on exposure to light. It is insoluble in water, is freely soluble in alcohol, and is miscible with acetone, chloroform, ether, fats, and vegetable oils.
Functional Use in Foods: Nutrient; dietary supplement; antioxidant.
Requirements
Labeling: Label claims in terms of former International Units (IU) should be based on the following 1 mg DL-a-tocopherol = 1.1 IU
Identification:
A. Dissolve about 10 mg of the sample in 10 mL of absolute alcohol, add with swirling 2 mL of nitric acid, and heat at about 75o for 15 min. A bright red to orange color develops.
B. The retention time of the major peak (excluding the solvent peak) in the chromatogram of the Assay Preparation is the same as that of the Standard Preparation, both relative to the internal standard, as obtained in the Assay.
C. If the isomeric form is not otherwise known, determine the optical rotation on a 1 in 10 solution of the sample in chloroform. The specific rotation is not appreciable (approximately +/- 0.05o).
Assay: Not less than 96.0% and not more than 102.0% of C29H50O2.
Heavy Metals (as Pb): Not more than 10 mg/kg.
Acidity: Passes test.
Tests
Note: In the following Assay, use low-actinic glassware for all solutions containing tocopherols.
Assay:
Internal Standard Solution: Prepare a solution in n-hexane containing 3 mg of hexadecyl hexadecanoate, accurately weighed, in each mL
Standard Preparation: Dissolve about 30 mg of USP Alpha Tocopherol Reference Standard, accurately weighed, in 10.0 mL of the Internal Standard Solution.
Assay Preparation: Dissolve about 30 mg of the sample, accurately weighed, in 10.0 mL of the Internal Standard Solution.
Chromatographic System: Use a gas chromatograph equipped with a flame-ionization detector and a glass-lined sample-introduction system or on-column injection. Under typical conditions, the instrument contains a 2-m x 4-mm borosilicate glass column packed with 2% to 5% methylpolysiloxane gum on 80- to 100-mesh acid-base washed silanized chromatographic diatomaceous earth. The column is maintained isothermally between 240oand 260o, the injection port at about 290o, and the detector block at about 300o. The flow rate of dry carrier gas is adjusted to obtain a hexadecyl hexadecanoate peak approximately 10 to 20 min after sample introduction when a 2% column is used, or 30 to 32 min when a 5% column is used.
Note: Cure and condition the column as necessary.
System Suitability: Chromatograph a sufficient number of injections of a mixture in n-hexane of 1 mg/mL each of USP Alpha Tocopherol Reference Standard and USP Alpha Tocopheryl Acetate Reference Standard, as directed under Calibration, to ensure that the resolution factor, R, is not less than 1.0.
Calibration: Chromatograph successive 2- to 5-mL portions of the Standard Preparation until the relative response factor, F. is constant (i.e., within a range of approximately 2%) for three consecutive injections. If graphic integration is used, adjust the instrument to obtain at least 70% maximum recorder response for the hexadecyl hexadecanoate peak. Measure the areas under the major peaks occurring at relative retention times of approximately 0.51 (a-tocopherol) and 1.00 (hexadecyl hexadecanoate), and record the values as AS and AI, respectively. Calculate the relative response factor, F, by the formula
( AS / AI ) x ( CI / CS )
in which CI and CS are the exact concentrations, in mg/mL, of hexadecyl hexadecanoate and of USP Alpha Tocopherol Reference Standard in the Standard Preparation, respectively.
Procedure: Inject a suitable portion (2 to 5 mL) of the Assay Preparation into the chromatograph, and record the chromatogram. Measure the areas under the major peaks occurring at relative retention times of approximately 0.51 (a-tocopherol) and 1.00 (hexadecyl hexadecanoate), and record the values as aU and aI, respectively. Calculate the weight, in mg, of DL-a-tocopherol in the sample by the formula
( 10CI / F ) x ( aU / aI )
Heavy Metals: Place a 2-g sample in a silica crucible, and proceed as directed in Method II under the Heavy Metals Test, Appendix IIIB, using 20 mg of lead ion (Pb) in the control (Solution A).
Acidity: Dissolve 1.0 g of the sample in 25 mL of a mixture of equal volumes of alcohol and ether that has been neutralized to phenolphthalein TS with 0.1 N sodium hydroxide, add 0.5 mL of phenolphthalein TS, and titrate with 0.1 N sodium hydroxide until the solution remains faintly pink after shaking for 30 s. Not more that 10 mL of 0.1 N sodium hydroxide is required.
Packaging and storage Store in tight containers blanked by inert gas and protected from heat and light.
Reference: FCC IV
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