Paper chromatography ascending development

For the separatory determination of pyridoxine in multi-vitamin preparations, other vitamins are separated by paper chromatography in which the upper layer of butanol-ammonium hydroxide-water (4 1 5) are used as the developer, and by the one-dimensional ascending method (102). 

The different methods of arranging the filter paper in the chromatographic chamber have been applied to sugar separations descending, ascending,39 40 and circular or horizontal development.41 These methods and other techniques will be discussed below. Detailed descriptions of the equipment needed for paper chromatography are readily available.8... 

The usual two-dimensional chromatography is a multiple development method in which the sample is spotted in the corner of a square of paper and ascending or descending development is made successively with two different solvents in two directions perpendicular to each other. Between developments, the paper is thoroughly dried to remove all traces of the first solvent. The best separations of complex mixtures are obtained if different types of solvents are employed. 

The range of development techniques available in paper chromatography is similar to those employed in TLC, namely, ascending, descending, radial. 

Paper chromatography, transition metals, ascending and horizontal development. 

Figure 21.10. Developing chambers for paper chromatography. A Ascending development B Descending development. Note that similar chambers are used in TLC. From D. Abbott and R. S. Andrews, An Introduction to C3iromatography, Boston Houghton Mifflin, 1965, by permission of the publisher.

The simplest and cheapest technique is paper chromatography, where the chromatographic bed consists of a sheet of paper, i.e., cellulose. The stationary phase consists of water adsorbed to the cellulose as well as of the polymer itself, although ion exchange and complexation processes may play an important role. The sample solution is applied as a spot near one end of the paper. A few centimeters of the sheet are dipped into the mobile phase which then ascends (or descends, as descending mode is also possible) into the stationary phase. When the mobile phase has almost reached the other end of the sheet the paper is removed from the developing tank and dried. If the analytes are not visible because they are not colored, the sheet is treated with a reagent to visualize the spots. 

Both descending and ascending paper chromatography have been employed on Whatman 3MM paper. The chromatograms were developed with an r -butanol-acetic acid-water (volume ratios, 120 30 50) solvent system. 

Figure 10.6. Developing chambers for plane chromatography (a) descending— used with PC (b) ascending—used with TLC and PC (c) sandwich—used with TLC (d) horizontal—used with paper as shown, but also adaptable for HPTLC.

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