ABSTRACT
Izmailov and Schraiber [8], in 1938 at the Institute of Experimental Pharmacy of the University of Kharkov, used a horizontal 2 mm layer of aluminum oxide without binder on a glass microscope slide for circular chromatography of alcoholic plant extracts such as belladona, reported in the Russian Pharmacopeia VII. The use of a thin layer, or open column, may have been suggested by the wider adoption of Tswett's column chromatography method by the late 1930s. Izmailov and Schraiber placed one drop of the pharmaceutical sample solution on the adsorbent and developed it into concentric zones by dropwise addition of methanol on the spot to produce circular zones of substances that were seen under an ultraviolet (UV) lamp. This method has been called spread-layer chromatography in some sources. The authors pointed out the usefulness of drop chromatography for testing adsorbents and solvents for application in column chromatography, compared to which it was faster and economical in terms of adsorbent, solvent, and sample usage.
