Thin-layer stick chromatography using silicagel cellulose: Studies on thin-layer stick chromatography. I

A new and simple technique for thin-layer chromatography (TLC) was devised by use of glass sticks in place of glass plate. The glass sticks used wereslim glass tubes of 2.3 mm in diameter and 20 cm in length. The adsorbent were uniformly spread over the surface of the glass sticks which were passed vertically through a funnel in which the adsorbent mixture was filled. The mixture was consisted mainly of silicagel with finegrade cellulose and soluble starch. After the heat activation of the adsorbent at 80100°C for 30 minutes, the layer of the adsorbent on the stick showed a smooth surface, and the thickness of the layer measured by micrometer was 1) 98μ, 2) 100 μ, and 3) 70 μ depending on the kind and the size of the sticks. The mean deviation of the thickness of the layer at the upper, center and lower parts of the sticks were 1) 8.07, 8.12, 8.91, 2) 4.15, 4.15, 2.30, and 3) 8.20, 7.72, 8.41, respectively. Such characteristics as velocity of development, Rf values, spot detectability were well comparable to those in the ordinary TLC method as shown in the studies with standard dyes. Some examples of applicational uses are shown, which were quite satisfactory. To assess the efficiency of the method devised, an attempt was made to detect Japanese rhubard (Rheum undulatum Linné) in rhubarb root powder (Rheum pamatum Linné). Crude preparations of plants analogous to R. palmatum Linné essentially contain rhaponticin which fluoresces (bluish violet) under UV irradiation at a wavelength of 3650 Å. Samples of rhubarb root powder, containing known graded concentrations of R. undulatum Linné pulvis from 0 to 0.5 per cent were tested by a method to detect the latter component; each sample was extracted with 10 ml of ethanol and 5 ml of the extract analyzed on thin-layer chromatographic sticks (S-C) with the developing solvent mixture (1), iso-propylether : n-butanol : methanol (27 : 7 : 7), and (2) water and by reading the chromatograms with UV illumination. R. undulatum Linné contained in the sample at concentrations down to 0.1 per cent was found demostrable by the test system. Attempts were also made to determine whether dipping the developed chromatographic stick in a color reagent solution rather than spraying it with the color reagent might be practicable with satisfactory efficiency. Namely, sticks developed for three sulfa drugs (0.5% in aceton) respectively with a solvent mixture (ethyl acetate : benzene; 3 : 1) were allowed to dry in air and then immersed