edited by
JOHN H. WOTlZ Southern Illinois University Carbondale. Illinois 62901
An Early Application of Paper Chromatography Frederick Kurzer Royal Free Hospital School of Medicine (Uniuersity of London) 8 Hunter Street London WC1 Scientific discoveries of any consequence are rarely made in complete isolation, hut are generally preceded by developments that approach them in varying degrees in thought or practice and are therefore the culmination of a continuous nursuit snannine" manv.vears. However. this continuitv in the advancement of science does not diminish the merit of the final achievement, which by the realization of some vital relationship, by a critical change of emphasis, or by its timeliness, reveals the discovery in its true and full significance. I t is well known that the introduction of chromatography, in its various forms. which has contrihuted so s~ectacularlv to the progress of ail branches of chemical science in recent years, has not been without its forerunners. Earlier ohservations in this field have been traced in Heftmann's (1)general outline of the history of chromatography, and individual techniques have been the suhject of separate historical reviews (2,3).It is the object of this brief note to draw attention to an early example of the application of paper chromatography in analytical practice. Observations that are evidently the consequence of partition phenomena between liquids supported on thin layers were described more than 100 years ago by Runge (I), Schoenhein (I ), and especially by Goppelsroeder (I, 4), who investieated the senaration and isolation of substances on " strips of filter paper or other fibrous materials, from solutions of their mixtures. Go~nelsroedersummarized his work. extending over some 46 ;ears, in a substantial hook (4) that a ~ n e a r e din 1901. and must he reearded as a classic in its field (&e Fig. I ) . He ascribed his obs&vations to the operation of ca~illarvefferra. but his tarhniaue is rlearlv recomi7able. both h i his description and illustraiions (see Fig. 2jas ascending DaDer chromatoaranhv. Althoueh laraelv em~iricalin character, the work isrema&able for its widk scopeand the minute attention to detail. The varietv of materials examined for their "capillary" properties ranged from inorganic salts, synthetic and natural organic dyes to food products (e.~.mineral waters, wines, beer, &d spices) and biological fluids (e.g. milk, hile, urine). The usefulness of the method for analytical purposes, especially the identification of traces of materials, was clearly envisaged (4), and its occasional use in technical and industrial practice has been alluded to (la). I t is therefore not without interest to discover fully docuThis column is a series of short articles on the less known events that contrihuted to important and interesting developments in chemistry. Manuscripts, of ahout two double-spaced, typewritten Dazes . " and othei inouiries should be addressed to the column editor. Dr. John Wotiz, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois 62901.
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Figure 1. Title page of Goppelsroeder's monograph. Copy, wifi the auThor's manuscript dedication, in the possessionof me Library of me Chemical Society. London.
Figure 2. Goppelsroeder's apparatus. The illustration shows the method of suspending ships of filler paper or fibrous material in solutions of me subsfancss being examined. The use of a bell jar for performing the operation in a closed space is specially noteworthy.
mented examples of the early use of paper chromatography in routine analytical practice. Such an example, in the area of food analysis, is found in Barthel's monograph (5) on the chemical control of dairy products. The book, first published in 1907, has been re-issued several times (5a), and appeared in an English translation in 1910 (5b). It includes a chromatographic method of detecting the addition of artificial coloring to milk products: the close approach of the technique Volume 55, Number 5. May 1978 / 321
t o present-day practice is apparent from the detailed experimental directions, which are reproduced in full as follows.
In this way many of the usual eoloring substances used in the dairy can he detected, but there are several that are not."
The Detection of Artificial Coloring in Milk and Dairy Products ( 5 b )
Since the method is stated bv t h e Swedish author ( 5 ) t o have been developed in the 1nst;ute of Hygiene in ~ a r n b & it was n o doubt fullv established bv t h e time it was incoroorated into t h e monograph in 1907 i s a "reliable and tested" method, and may well have been employed a t the turn of the Century, if not before.
"One hundred to two hundred c c . of milk or cream are made faintly acid with acetic acid, or are allowed to sour spontaneously, and are then warmed to 80'C. The curd, whichcontains fat and the coloring substance in addition to the protein matter, is separated from the serum by filtration through a cloth, digested twice with water to remove milksugar, and then well pressed. Themoist curd is boiledrepeatedly with alcohol until no color remains, and the combined d coholic extracts are evaporated to 10 or 20 c.c To the residue an equal quantity of absolute alcohol is added, and the whole left in the icechest for twelve hours. At the end of this time the solution will only contain a little fat, and any coloring matter which is present will he noticeable. A strip of filter paper is now dipped into the liquid, which rises slowly by capillary attraction to the height of the edge of the beaker and then evaporates. When themilk is pure a faint yellow or brown hand of colour forms on the upper part of the paper, whereas any added calouringmatter causes a more pronounced shade, varying from pink todeep orange, to form below the band given by pure milk. The strip of paper is freed from fat hy washing with petroleum ether, which does not attack the coloring matter or the paper fibre.
322 1 Journal of Chemical Education
Literature Cited (1) Heftmann,E., (Editor): "ChmmatographyALabonrtny H a n d b m k o f C k o m a ~ a p h ' ~ and Eloetrophomtic Methods," Van Nmttand Reinhold Co., N c v York ( 8 ) let Ed. (hl 3rd Ed 1975: Chap. I, pp 1-13, and references given 1961, Chap. 1, pp. ?4
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(2) Peiick, N., Balliw, H. R.. and Mangold, H.. in "Advances in Chromatography", Voi.
3 (Editor: Diddin-, J. C., and Keuer, R. A,) DeLLer, New Yorh, 1%6, p. ffi (thin layer ehromstography). 1971.8 (gas ehm(31 Ettre, L. S.,Anal. Chem., 1971, dJ 20A; Intern. Lib., JuI-A-a, mstogrsphy). (4) Gwmlsmeder. F.. "Csdllarsnalvre. Beruhend auf C e o i h i e t a - u n d Ad~omtionaers~hoinungon",Birkheuser, B&l, 1901. (5) (a) Barthe&Ck., "Die Methoden mr Untersvchunguon M&h und MolLmiprcduLten." lat Ed. Leipzlg, 19W,2nd Ed.Leipig, 1911.3rdEd. Berlh I9ZO;Uh Ed.Berh, 1928. (h) Barthel, Chr.,"Methods used in the Examination of Milk and Dairy Product$", (Tronalnlor Goodwin. W.1 Mamillan, London. 1919, p. 116.
