The Renaissance

In fact, Willstatter had first-hand knowledge of chromatography because he owned a German translation of Tswett's book (the translator is unknown). Later the translated text came into the possession of Richard Kuhn, a professor of chemistry at the Kaiser Wilhelm Institute for Medical Research at Heidelberg, Germany; Kuhn was a former student of Willstatter. In 1930, Edgar Lederer joined Kuhn as a postdoctoral fellow. His task was to separate xanthophyll

(today called lutein) and zeaxanthin (Figure 4), and he was able to solve this problem after reading Tswett's book. Lederer used what we would call today preparative columns - glass tubes with a diameter of 7 cm. The results were published in three papers which appeared in leading German scientific journals in 1931. These articles mark the breakthrough and acceptance of chromatography. The method was successfully used in the laboratories of Nobel prize-winners Paul Karrer and Leopold Ruzicka (who received the award in 1937 and 1939, respectively; Kuhn was awarded it in 1938). All these scientists were active in the isolation and structure elucidation of natural compounds, and chromatogra-phy was an invaluable help to them.

The main problem in these years was how to find suitable stationary phases. Systematic tests and good luck were necessary to establish adsorbents such as alumina, magnesia and silica. Some researchers began to elute the chromatographic bands from the column instead of cutting the packing; however, it is not clear who used this technique first. It was proved that chromatography can be used on a large scale; Winterstein was able to obtain gram quantities of chlorophylls by using 12.5 cm i.d. columns.

The first application of chromatography to compounds other than organic molecules was done by Georg-Maria Schwab in Munich, Germany. In 1937 he separated inorganic cations on alumina. The first enantioselective separation was performed by Geoffrey M. Henderson and H. Gordon Rule, also in 1937. They were able to partially resolve (R,S)-phenylene-bis(iminocamphor) on lactose with petroleum-benzene 8 : 1 as the mobile phase.

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Solar Panel Basics

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