Letter to the Editors

Leslie S. Ettre Encyclopedia of Industrial Chemical Analysis 345 Westchester Avenue Port Chester, N. Y. 10573

Does Chromatography really mean Color Writing?

The November 1969 issue of Chromatographia published the letter of Dr. Large [1] in which he was proposing to eliminate the term "chromatography" and the related expressions such as "to chromatograph" and "chromato- gram", and replace them by the term "sorption analysis" and expression, " to sorptograph", and "'sorptogram". Dr. Large mentions that the term "chromatography" was used by Tswett because in his work color differences of the separated substances played an important role. Actu- ally, Tswett in his publication [2a] does not state this specifically although his statement had been interpreted in this way:

"Like light rays in the spectrum, the different components of a pigment mixture, obeying a law, separate on the calcium carbonate column and can thus be qualitatively and quantitatively determined. I call such a preparation a chromatogram and the corresponding method the chro- matographic method."

It is probably true that in the chromatography of today, color differences play no role (although our friends in paper- and thin-layer chromatography might object this statement), and thus, the term - as originally conceived - lost its assumed meaning. However, this fact does not represent any real contradiction because if the sample components are colored, the separated fractions will cer- tainly be of different color. Actually, Tswett, in his very first paper already emphasized that "chromatography" can also be applied equally weU to colorless substances [2b]:

"It is self-evident that the adsorption phenomena described are not restricted to the chlorophyll pigments, and one must assume that all kinds of colored and colorless che- mical compounds are subject to the same laws."

Even if the term "chromatography" would have lost its original meaning, it would not make the change of a well- established term necessary. After all, there are many ex- pressions common in today's usage which now have a quite different meaning. For example, the same issue of Chromatographia reports on the Fifth International Symposium on Separation Methods held in Lausanne and proves that the subject of this meeting was certainly not (only) what its name says ("symposion" = a drinking party; "syn posis" = with a drinking). Also, one should

not forget that the expression "sorptometer" and "sorptogram" are today commonly accepted to describe the technique of surface area measurement by the conti- nuous flow method [3, 4].

But, apart of these arguments, we must raise tile very important -- and valid - question: did Tswett really call the technique "chromatography" because of the different colors of the separated fractions?

The interesting fact is namely that the surname of Tswett, a Russian subject, is identical with the Russian word for color (UBET). Although this question was raised as early as in 1940 by Campbell-Gamble [5], it was appa- rently overlooked, and although, in 1962, Purnell in his book [6], drew again our attention to it, it is still not widely known. In other words, it is quite possible that Tswett actually named the technique, invented by him, after himself. As expressed by PurneU, "it was presumably the formation of the coloured solute rings that suggested the name 'chromatography' but it would be nice to think that Tswett, whose name, in Russian, means colour, took advantage of the opportunity to indulge his sense of humor."

Of course, we shall never know what was in Tswett's mind when he formulated his term; however, the fact that he selected it although he already recognized that differences in color are not the prinicipal characteristics of his technique, and the lack of the word "therefore" which really should couple the two sentences in the first quotation, corroborate this speculation.

The point I want to make is that if one does not like to relate the term "chromatography" to the separated colo- red fractions of Tswett, there is no reason why it could not be interpreted as related to the name of its inventor.

If we speak about Roentgen-rays, measure the pressure in Toricelli units, utilize the technique of Galvani in galvani- zing, use a Bunsen burner in our laboratory, and follow the Dumas, K]eldatd and Pregl methods in microanalysis, why should we not accept that the technique in which so many of us have found enjoyment is perpetuating the memory of its inventor, and that the piece of paper we have just pulled off the recorder actually shows Tswett's writing?

Chromatographia 3, 1970 Letter to the Editors 95

The Original German of the two Quotations from Tswett's Publication:

"Wie die Lichtstrahlen im Spektrum, so werden in der Calcium Karbonats~iule die verschiedenen Komponenten eines Farbstoffgemisches gesetzm~ifSig auseinandergelegt und lassen sich darin qualitativ und auch quantitativ be- stimmen. Ein solches Pr~iparat nenne ich ein Chromato- gramm und die entsprechende Methode die chromato- graphische Methode."

,,Selbstverstfindlich sind die beschriebenen Adsorptions- erscheinungen nicht nur den Chlorophyllfarbstoffen eigen, und es ist anzunehmen, dat~ allerlei gef~irbte oder farblose chemische Verbindungen denselben Gesetzen unterworfen sind."

Literature

[1] E. Lange, Chromatographia 2,517 (1969). [2] M. Tswett, Ber. dtsch, bot. Ges. 24, 316-323 (1906);

a p. 322, b p. 323. [3] L. S. Ettre, N. Brenner and E. W. Cieplinski, Z. phys. Chem.

(Leipzig) 219, 17-35 (1962). [4] E. Cremer and H. Huck, Glastechn. Ber. 37, 511-515 (1964). [5] D.J. Campbell-Gamble, Chem. & Ind. 59,598 (1940). [6] 11. Purnell, Gas Chromatography. J. Wiley & Sons, New York,

London 1962; p. 1.

Received January 18, 1970

Announcement

Automatisme et Chromatographie

Le Centre de Perfectionnement des Industries Chimiques organise parall61ement h son cycle de perfectionnement <<Automatisme et Chrornatographie>~ une Exposition de Mat6riel Scientifique Industriel et de Laboratoire. Le th&ne de cette exposition sera: <~Traitement automatique de l 'lnformation chromatographique>~.

Cette exposition se tiendra duil au 14 Mai 1970 dans les locaux de l'Ecole Nationale Sup6rieure des Industries Chimiques, rue D6glin - 54-Nancy - T61.52 01 42, poste 226.

Le mat6riel expos6 dans le cadre de cette exposition sera le suivant: ckromatographes, int6grateurs (rn6caniques, 61ectroniques... ), calculateurs analogiques et digitaux (munis de convertisseurs analogique-num6rique), chatnes d'acquisition et de traiternent de signaux analogiques (enregistreurs magn6tiques.. . ).

Contazt: M. Pierre Su t re , Ensic, rue Henri-D6glin, 54-Nancy

96 Chromatographia 3, 1970 Letter to the Editors