The classical method of chromatography of chlorophylls and carotenoids on an adsorbent column is somewhat time-consuming and is more suitable for separating larger quantities of pigments. Therefore many authors have tried to develop a simpler method of separating these substances on paper. With the methods that have been described in the literature it is possible to analyse quantities of pigments of the order of x0-8 g. In recent years various modifications of these methods have been described
and they have been used on a larger scale than before (more than 50 articles since 1952). Some of these articles have been reviewed in three communications16*m*b6. In this paper we are attempting to give a more complete list of articles on paper chromatography of plastid pigments. Modifications of the methods that have been described in the literature are summarized in Tables 1-5 (pp. 196-205).
I. OLDER PUBLICATIONS
The first time a separation of plastid pigments on paper was mentioned, was in 1906.
At that time the founder of chromatography, M. Tsw~fl, described a separation of pigments from an aqueous alcohol solution by capillary analysis. As a result he obtained five zones most of which were close together. At the bottom of the paper strip a zone containing a mixture of all the pigments was found, then came the following zones, in ascending order: carotenes, chlorophylls, xanthophylls. Capillary analysis, from a mixture of ethyl ether and 96% ethanol (I:I to 1:2), was also used by KYLIN~ for the detection of carotene, xanthophyll, phyllorhodin, fucoxanthin and chlorophyll in saponified extracts of higher plants and brown algae.
BROWN~O experimented
with the circular chromatographic method on blotting paper. The paper, 15 x 15 cm (untreated or impregnated with aluminium hydroxide), was sandwiched between two glass plates. The solution of pigments in carbon disulfide was placed on the paper through a 6 mm hole at the centre of the upper plate. The chromatogram was developed by adding the pure solvent drop by drop. STRAIN (ref. $3, p. 77) briefly mentioned the separation of pigments on paper by developing with aqueous ethanol. The possibility of separating pigments on wide sheets of paper or on cylinders of paper was proposed by ARONOFF (ref. 3, p. 55; see*), the chromatograms being developed repeatedly with petroleum ether.
2. EVOLUTION OF THE METHOD SINCE 1952
Although MARKUS and ASAMI reported their experiments with paper chromatography of plastid pigments at two scientific meetings as early as 1951, and although ASAMI References p. 207.