Principle

In this investigation, a uniformly green raw extract of
fresh leaves is first separated into different fractions
by means of column chromatography. To do so, the
extract is added to a column filled with starch and drawn
through the column under slightly reduced pressure (to increase the
flow rate of the mobile phase) with ligroin as the eluent. A
separation occurs in a clearly recognisable, broad, yellow area and
in a narrow, green band. This means that the xanthophylls (yellow)
are separated from the chlorophylls (green). If the vacuum is
reduced during the separation, the separation is much better, but
then separation also takes considerably longer. Each of the
separation fractions can be collected individually and
characterised by recording their absorption spectra, if necessary,
or examined for fluorescence by radiation with UV light.

Tasks

Investigate different leaf pigments using column
chromatography.

What you can learn about


Chlorophyll

Column chromatography

Leaf pigments

Xanthophyll