Separation and Estimation of Organic Compounds
Introduction
Chromatographic techniques are used to examine the coloured components (which include carotene and chlorophyll) of a mixture obtained by extraction of green leaves with acetone, and to separate the carotene from the other components. Students use two types of chromatography, thin layer and column chromatography, the former illustrating to the students the feasibility of separating components and the latter being used to separate the carotene to allow its quantitative determination. Spectrophotometry .gif) is used to determine the percent by weight of each of chlorophyll and carotene in the leaves. The amount of chlorophyll in the leaf extract mixture can be quantified without its isolation from the leaf extract mixture.
Column chromatograhpy is needed to separate the terpenes in the mixture - in this process,
β-carotene is separated from xanthophylls such as lutein and rhodoxanthin. The image above shows the solution containing β-carotene, with the other yellow components still adsorbed to the column in the background.
Chromatography and spectroscopy are useful techniques not only for organic chemists and chemists in general, but also for biologists and health scientists. Students majoring in biology and health sciences are a significant cohort in year 1 classes at the University of Auckland.
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