QUANTITATIVE DETERMINATION OF VITAMIN A AND VITAMIN E

QUANTITATIVE DETERMINATION OF VITAMIN A AND VITAMIN E

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  QUANTITATIVE DETERMINATION OF VITAMINA AND VITAMIN E
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  VITAMINS  Vitamins arenaturally occurring organic compounds that are essential to metabolic or other functions in the body.  Most vitamins cannot be synthesized by the body. They must be supplied in the diet.  Vitamins are usually classified as water soluble or fat soluble
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  CLASSIFICATION OF VITAMINS Vitamins can be classified as either • Water soluble • Fat soluble.  Water soluble vitamins are generally involved in the cellular metabolism of energy supplying nutrients.  Fat soluble vitamins often have very specialized functions
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  Water Soluble Vitamins Examples of water soluble vitamins Vitamin C Vitamin B1 (Thiamine)
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  Fat Soluble Vitamins Common fat soluble vitamins include • A, • D, vitamin A • E, • K.
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  Vitamin A Sources Commonly found in cod liver oil, green vegetables, and fruits.  Carrots indirectly serve as a source of vitamin A since they contain β carotene which the body readily converts to vitamin A
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  Vitamin A Functions Vitamin A is fat soluble.  It is not readily broken down by cooking.  Role in aiding in night vision.  Vitamin A Deficiencies  A deficiency in vitamin A results in night blindness.  The most serious deficiency results in a condition known as Xeropthalmia, a severe form of conjunctivitis or blindness.
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  Vitamin E sources vitamin E can be found most abundantly in wheat germ oil, sunflower, and safflower oils and also in nuts, cereals, olive, tomato, spinach, blue crab. olive nuts cereals
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  Vitamin E functions Vitamin E is used to refer to a group of fat-soluble compounds that include both tocopherols and tocotrienols.  α-Tocopherol is an important lipid-soluble antioxidant.  α-Tocopherol has a regulatory effect on enzymatic activities  responsible for the repair of the wounds and regeneration of the extracellular tissue, vitamin E also plays a role in neurological functions, and inhibition of platelet aggregation
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  Quantitative determination of vitaminA  Category: antixerophthalmic vitamin  Structure:  Standards: not less than 95% and not more than 110% of standard number of units of vitamin A per g.
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   Identification: exhibitsa maximum at about 325- 327nm.  QUANTITATIVE ESTIMATION METHOD:  UV-Spectrophotometric method  principle:  it absorbs the UV-radiation ranges from 200nm to 400nm.  Valence electrons absorb the energy, there by molecule undergo transition from ground state to excited state.  By the absorption peaks the nature of electrons and molecular structure can be elucidated.
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   METHOD:  Dissolvean accurately weighed quantity of the substance in cyclohexane to give a solution containing 9 to 15 units of vit A per ml.  Determine the wave length of maximum absorption.  Measure the absorbance of the solution against cyclo hexane at 328 nm.  If the wave length of maximum absorption lies between 326 and 329 calculate the vit A potency of the sample from the expression A328(A1% 1cm) × 1900 = vit A potency in units per g.
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   If therelative absorbances are not within the limits then calculate a corrected absorbance at about 328nm by applying the observed values to the equation A328(corr.) = 3.52 (2A328 –A316 – A 340)  If the wavelength of maximum absorbance lies out side the range of 323 to 327 then the unsaponifiable fraction of the sample must be further purified by chromatography.
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  Quantitative determination of vitaminE  Category: anti oxidant  Structure:  Standards: it contains not less than 96% and not more than 102% of C31H52O3.
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  QUANTITATIVE ESTIMATION METHOD: Chromatographicmethod: Principle:  The principle of separation in GAS CHROMATOGRAPHY is partition.  They travel according to their partition coefficients towards the stationary phase.  More soluble travels slower  Less soluble travels faster  No two components have same partition coefficients.  The components are separated according to their partition coefficients.
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   METHOD:  Internalstandard solution: dissolve an accurately weighed quantity of hexa decyl hexa decanoate in n- hexane to obtain a solution having a known concentration of about 1mg per ml.  Standard preparation: dissolve in internal standard solution a suitable quantity of USP alpha tocopherol RS to obtain a solution having known concentration of 1mg per ml.  Assay preparation: transfer 50mg of vitamin E to a 50ml volumetric flask, dissolve in internal standard solution, dilute with internal standard solution to volume and mix.
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  Chromatographic system  TheGC instrument is equipped with a flame ionization detector.  It contains 2m-4mm borosilicate glass column packed with 2% to 5% liquid phase on 80 to 100 mesh support utilizing a column injection.  The column is maintained at a temp. between 245° to 265°
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   The injectionport and detector block are maintained at about 10° higher than the column temperature.  The flow rate of dry carrier gas is adjusted to obtain a peak approximately 18 to 20 min after sample introduction.  Procedure:  Inject a suitable portion (2-5µl) of the assay preparation into a suitable gas chromatograph.  Record the chromatogram .  Measure the areas under the 1st(alpha tocopherol) and 2nd major(hexadecyl hexa decanoate)peaks, record the values as aU and aD respectively.  Calculate the quantity in mg, of vit E taken by the formula (50CD/F)(aU/ aD) Where CD is conc.in mg/ml F is the relative response factor
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  REFERENCES  INDIAN PHARMACOPOEIA BRITISH PHARMACOPOEIA  UNITED STATES PHARMACOPOEIA  www.googleimages.com  www.wikipedia.com  www.cyberlipid.org
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