Paper chromatography continuous

In 1944, about the time Sanger determined the primary structure of insulin, two-dimensional paper chromatography became available for analyzing amino acids of protein samples.32 This method allowed Sanger to analyze 20 amino acids in a single run with considerably less sample and time compared to the previous methods. The development of an automated amino acid analyzer in 1958 by Spackman, Stein and Moore had made further progress.33 This first amino acid analyzer performed an analysis with 1 pmol of sample in 20 hours. Due to the continuous improvements made on amino acid analyzers,... 

There are two popular LC techniques in which the stationary bed is supported on a planar surface rather than in a column paper chromatography (PC) and thin-layer chromatography (TLC). PC preceded TLC by some 10 to 15 years, and a large number of excellent separations were devised for it. But beginning about 1956, it was found that TLC could also be used for most of these separations and that it was faster, more reproducible, more versatile, and more convenient. As a result, most laboratories have abandoned the use of PC with its large cumbersome glass chambers. Those who have not, continue to use PC because they feel that the original PC methods are superior or because of the lower cost of PC. 

For more complex feed mixtures other approaches for continuous operation of the chromatographic separation have to be considered. One example is annular chromatography with a rotating stationary phase. This concept was developed in the 1950s as a continuous method for paper chromatography by Solms (1955). In annular chromatography the stationary phase is packed between two concentric cylinders and rotates around a central axis (Fig. 5.14). 

The papers published during the past year in the field of nucleotide and polynucleotide chemistry have been less remarkable for innovative chemistry than for biochemical application, and sheer volume has necessitated much pruning of the material available. The appearance of a new journal - Nucleic Acid Research - is symptomatic of the increasing publication in this area. Cyclic AMP research, Sutherland s monument, has yielded many new compounds, and no attempt has been made to cover the huge quantity of biochemical and pharmacological data available on these, for which the reader is advised to seek specific reviews. Affinity labelling and affinity chromatography continue to justify the wide research effort they command. 

The apparatus used for continuous-flow paper electrophoresis can be used for separation with an elution rather than a continuous-flow method. The sample is spotted at the top of the paper and only the buffer solution is continuously added. If the electrophoresis is stopped before the sample components drip from the bottom of the paper, the technique combines the separating ability of descending paper chromatography (separation occurring vertically) with that of electrophoresis (separation occurring horizontally) to yield spots simultaneously developed in two dimensions. 

Since the early 1970s paper chromatography has gradually given way to thin layer though it still offers a few advantages in comparison to TLC, for instance, in cost, effectiveness in separating polar and water-soluble compounds and without elaborate modification continuous development... 

The work was continued on the paper chromatography modeling of UF oligomers [72]. In this series of experiments the limits of the molecular mechanics approach finally started to become apparent. While a good trend correspondence with experimental Rf values was again obtained within each of the two series of UF oligomers tested, correspondence was lost when one tried to compare the compounds within a series with the compounds of the other series. Thus, excellent correspondence existed within the homo-... 

Descending development is frequently used in paper chromatography, yet seldom in TLC. It neither shortens the migration time nor improves separation and continuous development is more easily achieved in another way (p. 69, 75). 

Excellent resolutions have been obtained on either cellulose MN 300 [3] or Avirin cellulose [4] with solvent systems previously used for paper chromatography. The data for the common sugars are summarized in Table 199. Where the sugars have low hi /-values multiple development is required (solvents IX and X) or the plate can be modified for continuous flow [4]. 

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