A NOTE ON THE SPECTROSCOPIC DETERMINATION OF THE VITAMIN A CONTENT OF PILCHARD OIL

1935 ◽  
Vol 13a (5) ◽  
pp. 93-98
Keyword(s):  
Vitamin A ◽  
Extinction Coefficient ◽  
Conversion Factor ◽  
Spectroscopic Determination ◽  
Cod Liver Oil ◽  
Biological Tests ◽  
Coloring Matter

An attempt has been made to measure spectroscopically the Vitamin A content of pilchard oil. Using the same conversion factor as for cod liver oil, measurements of the extinction coefficient at 3280 Å gave Vitamin A values much larger than those obtained by biological tests. It has been shown that this discrepancy cannot be wholly ascribed to either the coloring matter or the saponifiable material in the oil. A satisfactory check on the results can be obtained only when it is possible to remove completely the Vitamin A from the oil, without otherwise modifying it.

Spectrophotometric Determination of Vitamin A in Oils and Fats

1978 ◽  
Vol 61 (3) ◽  
pp. 753-755
Author(s):  
Teymour Kamangar ◽  
Ahmad B Fawzf
Keyword(s):  
Vitamin A ◽  
Acid Solution ◽  
Trichloroacetic Acid ◽  
Molar Absorptivity ◽  
Vitamin D2 ◽  
Cod Liver Oil ◽  
Trichloroacetic Acid Solution ◽  
Blue Reaction ◽  
Β Carotene

Abstract A spectrophotometric method for determining vitamin A based on interaction with 50% trichloroacetic acid solution in dichloromethane was developed. The blue reaction product had a maximum absorption at 620 nm and obeyed Beer's law over the concentration range of 0.5-5.0 μg retinol/ml solution. The molar absorptivity of the reaction product was 1.58 × 105. As much as 100 μg vitamin D2, and β-carotene up to 12 times the vitamin A concentration, did not interfere with the determination. The results obtained from the determination of vitamin A in cod liver oil and butter showed excellent agreement with the Carr-Price method, 43.013 (d).

Extract of Malt with Cod-liver Oil: determination of oil and vitamin A

The Analyst ◽  
1939 ◽  
Vol 64 (764) ◽  
pp. 795
Author(s):  
D. C. Garratt
Keyword(s):  
Vitamin A ◽  
Cod Liver Oil

A STUDY OF THE DETERMINATION OF VITAMIN A BY SPECTROPHOTOMETRY AND BY PHOTOELECTRIC COLORIMETRY

1938 ◽  
Vol 16b (12) ◽  
pp. 422-431
Author(s):  
W. D. McFarlane ◽  
A. J. Sutherland
Keyword(s):  
Vitamin A ◽  
Extinction Coefficient ◽  
Ultra Violet ◽  
The Other ◽  
Unsaponifiable Fraction ◽  
Complete Destruction ◽  
Significant Difference ◽  
Before And After ◽  
Absorption Measurements

A comparison has been made of the determination of vitamin A in cod-liver oils and concentrates of vitamin A by means of (a) extinction coefficient measurements at 3280 Å, and (b) photoelectric colorimetry. Both methods are shown to yield results of equal accuracy, but with cod-liver oils special precautions have to be taken in the preparation and purification of the unsaponifiable fraction. No significant difference was found between the means of the quotients, blue value/E value, for low potency cod-liver oils and those for concentrates.The estimation of vitamin A by direct spectrophotometric measurements before and after its destruction by intense ultra-violet irradiation has been investigated. The conditions are described which permitted the complete destruction of vitamin A in a concentrate with apparently no significant effect on the other absorbing constituents of the oil except carotene. The residual absorption after irradiation amounted to about 5% of the initial absorption. With cod-liver oils the values obtained by this method are 20 to 30% lower than those obtained by absorption measurements on the unsaponifiable fraction. The results obtained with the concentrate indicate that a correction may be applied which reduces the discrepancy to about 10 to 15%.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

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