Uma técnica para avialiação de α, β-caroteno e licopeno em material vegetal
Palavras-chave:
avaliação de caroteno, extração de carotenos, cromatografia de alumina, espectro de absorção, impurezas no eluatoResumo
The extraction and evaluation of a and g-carotene as well as licopene were performed by:
* Homogenization of the samples ina blender with known amounts of petrol ether.
* Chromatography in a column of alumina with 3% sodium sulfate suspended in petrol ether.
*Elution with the petrol ether itself.
*Optical density measurements at selected wavelengths.
* Estimation of contents by formulas according to our working conditions.
* Light as well as heavy petrol ether gave almost the same absorption spectrum of g-carotene.
* By chromatography we could separate two main fractions:
a) a and B-carotene together in one fraction:
b) licopene in the other fraction.
* The spectrum of the carotene fraction permitted the evaluation of the concentration of both its solutes and the amounts of 'impurities'. Relying on our results there were only traces of impurities, if any, in this fraction.
* Light conditions as usually found in our laboratory caused a decrease of 40% of carotene within two days.
* On the other hand, samples of elutes when kept in the dark showed an increase of optical density not due to evaporation of the solvent.
* In tomatoes the licopene fraction showed a spectrum which revealed no impurities.
Referências
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ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS. Official Me- thods of Analyses. 11. ed. Washington, 1970. 1015 p.
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LINSKENS,H.F. Papierchromatographie in der Botanik.Berlin, Springer Verlag, 1955. 253 p.
MAGALHÃES NETO, B.J.S. Introdução ao Estudo dos Carotenoides do Caju. Univ. Recife. Recife, 1952. 36 p. Tese Doc. Livre.
MOORE, T. Vitamin A. Amsterdam. Elsevier Publishing Company, 1957. 645 p.
MORTON, R.A. § ROSEN, D.G. Carotenoids, Vitamin A and 7- Dehydrosteroid in the Frog (Rana temporaria) Biochem. J. 45(5): 612-627. 1949.
STROHECKER, R. § HENNING, H.M. "g-Carotin". Em: - Vita- minbestimmungen. Darmstadt, Verlag Chemie GmbH, 1963. p. 62-67.
ZECHMEISTER, L. § CHOLNOKY, L. Principles and Practice of chromatography. London, Chapman e Hall Ltd., 1950. 361 Pp
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