1070-4272/05/7807-1073+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 7, 2005, pp. 1073!1076. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 7,
2005, pp. 1094!1098.
Original Russian Text Copyright + 2005 by Berezkin, Balushkin, Nepoklonov.
AND ION-EXCHANGE PROCESSES
Electroosmotic Circular Thin-Layer Chromatography
V. G. Berezkin, A. O. Balushkin, and E. B. Nepoklonov
Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, Russia
Received December 16, 2004; in final form, March 2005
Abstract-A new version of electroosmotic thin-layer chromatography, circular electroosmotic chromatogra-
phy, was suggested and a prototype apparatus for its implementation was designed.
In the recent decade, liquid thin-layer chromatogra-
phy (TLC) has been under intensive development. The
cheapness and high selectivity of the technique, as
well as its quite satisfactory performance and simplic-
ity, led to a wide use of TLC in various fields of
science and technology and in environmental monitor-
One of the most efficient versions of TLC is cir-
cular TLC, which was first suggested by Izmailov and
Shraiber  and is the first known kind of thin-layer
chromatography. The theoretical foundations and
experimental implementation of circular TLC, as well
as the advantages and shortcomings of the method,
were considered in detail in [1, 5, 6]. Compared with
the linear version of TLC, widely used in chromato-
graphic practice at present, the circular technique has
the following important advantages [1, 5]: higher
resolution, higher sensitivity of detection of chroma-
tographic bands (as a result of their narrowing, i.e.,
concentration), and lower expenditure of the mobile
phase. However, the version of circular TLC under
discussion also shows a number of shortcomings
[1, 5]: a decrease in the average flow velocity of the
mobile phase, poorer resolution in analyses for com-
pounds with high R
(0.6), and impossibility of im-
plementation of the two-dimensional version of TLC.
The basic specific feature of the chromatographic
process in circular TLC (compared with the linear
modification) consists in the existence of a velocity
gradient in the flow of the mobile phase along the
direction in which compounds being analyzed are
eluted. This leads to an automatic narrowing of chro-
matographic bands in circular TLC, i.e., to a higher
efficiency of chromatographic separation, because the
velocity at the peak front is smaller than that at its
It would be expected that application of the elec-
troosmotic effect in circular TLC should make higher
the motion velocity of the mobile phase, and effect of
narrowing of chromatographic bands, characteristic of
the conventional circular chromatography, must also
be inherent in circular electroosmotic TLC (EO-TLC).
Consequently, this version of EO-TLC must be more
efficient as compared with linear electroosmotic thin-
This study is devoted to development of a new
chromatographic method and design of a new ap-
paratus for implementation of circular EO-TLC and to
analysis of its basic chromatographic characteristics.
The figure shows schematically the apparatus for
the method under study.
The electroosmotic flow
of a mobile liquid phase in circular EO-TLC was
created using two electrodes: circular (positioned on
the periphery; outer diameter ~9 cm, inner diameter
~8 cm; stainless steel) and central electrodes.
The central electrode was placed in a glass tube
about 10 cm long, with an inner diameter of 7.5 cm.
The end of the glass tube, brought in contact with the
adsorption layer of a TLC plate, had a constriction
(inner diameter 0.5 mm, outer diameter 3 mm). The
glass tube was densely packed with a filter paper
moistened with the mobile phase. A Nichrome-wire
electrode (anode) was placed at the center of the tube.
The mobile phase was delivered to the central part of
the plate from the glass tube with the electrode at
the center of a circular piece of filter paper (8 mm in
diameter), placed in the central part of the TLC plate.
As compounds subjected to chromatographic analysis
served selected dyes or a mixture of these. The dye
mixture to be separated was deposited with a micro-
Designed at Institute of Petrochemical Synthesis, Russian
Academy of Sciences.