Published:Journal of Chromatographic Science, ISSN 0021-9665Volume 38, Number 3, March 2000, pp. 89–90

I started to write this editorial on January 1, 2000, and this was the first time that I used the date 2000. Such a major change—changing from one century, and even more significantly, changing from one millennium to the next—induces everybody to look back, evaluate the past developments, and also become engaged in prophecies, predicting all the great achievements one can expect from the next hundred years.

Chromatography is the child of the 20th Century. The first experiments of M.S. Tswett on the new separation technique were carried out in 1901–1902, and he reported on them in 1903. After a long incubation period, the technique went through many evolutionary steps, and practically every decade brought something new. Liquid adsorption chromatography—the technique used by Tswett—was followed by partition chromatography, which then was extended to the analysis of gases and vaporized samples. The principles of separation were further broadened by adding ion-exchange and separation by molecular size. All of these changes started a revolution in chemical, industrial, and biochemical analysis, transforming the early manual technique into a highly automated, instrumental method.

To evaluate a centenary evolution is a major task, and I leave it to more detailed, critical discussions. Rather, I shall briefly survey the evolution of chromatography since the start of our journal, in 1963, by Seaton T. Preston, himself a pioneer in the instrumentation of gas chromatography and a visionary who created this vehicle for the wide dissemination of information on the newest developments.

What was the status of chromatography in 1963? At that time, the most dominant technique was gas chromatography (GC). One decade after the seminal paper of A.T. James and A.J.P. Martin first describing gas–liquid partition chromatography (GLPC), it already had become one of the most widely used laboratory technique. It was used not only for the analysis of compounds that were gases at room temperature or could be easily volatilized, but even for many types of nonvolatile compounds that had to be converted to volatile derivatives prior to analysis; steroids and amino acids are classical examples for this. By the beginning of the 1960s, a number of companies supplied gas chromatographs not only for laboratory work but also for the automated analysis of process streams. Another variant of chromatography where instruments were already available was ion-exchange chromatography (IEC); the Amino Acid Analyzer developed in 1958 by S. Moore, W.H. Stein, and D.H. Sparkman at the Rockefeller Institute for Medical Research (today, Rockefeller University) permitted the automated analysis of complex biochemical samples. In addition, paper chromatography (PC) developed in 1944 by the group of A.J.P. Martin and particularly thin-layer chromatography (TLC) developed a decade later by E. Stahl were also popular, mainly because of their simplicity. Finally, a new branch of chromatography introduced in 1959 by P. Flodin and J.O. Porath and the Swedish Pharmacia Corporation started to gain importance in biochemistry: this was the so-called gel filtration permitting the separation of macromolecules by differences in their size.

This was the field of chromatography when the first issue of the Journal of Gas Chromatography—the predecessor of our current journal—was published in January 1963. As our readers can immediately recognize, one technique was missing from this enumeration: column liquid chromatography (LC), actually the oldest variant of chromatography. It is interesting to note that although A.J.P. Martin and R.L.M. Synge 20 years earlier had already described liquid–liquid partition chromatography in columns (in fact, for its invention they received the 1952 Chemistry Nobel Prize), it was used only by a few laboratories, and in practice, column liquid chromatography continued to be carried out essentially in the way done by Tswett 60 years earlier, using small glass columns packed with an adsorbent and a mobile phase flow controlled by gravity. Soon, however, major changes would take place.

The meteoric growth of gas chromatography also resulted in a much broader knowledge of the theoretical basis of chromatography. In turn, the conclusions gained in gas chromatography permitted one to recognize the shortcomings of classical liquid chromatography, mainly due to the three orders of magnitude slower diffusion in a liquid than in a gas. Thus, if the technique was to be improved, this slowness had to be overcome by other means, notably using small particles with a short diffusion path and higher velocities requiring high pressures. These requirements were already predicted by Martin and Synge in their fundamental 1941 paper; now, in the early 1960s, careful theoretical studies resulted in exact relationships permitting the establishment of the desired optimum conditions. Based mainly on the theoretical studies of J.C. Giddings at the University of Utah, the practical work of C. Horváth at Yale University, and the additional contributions of a few other key scientists, modern high-performance liquid chromatography (HPLC)—as the new variant was called in order to distinguish it from the classical version of liquid chromatography—became a reality in the second part of the 1960s.

A concomitant change in liquid chromatography was the introduction of the so-called bonded stationary phases consisting of long-chain organic moieties covalently bonded on silica particles. With their use, reversed-phase chromatography (RPC) using polar mobile liquid phases with the essentially nonpolar stationary phase became the predominant technique in high-performance liquid chromatography, particularly after Horváth established the theory describing the physico-chemical phenomena governing reversed-phase chromatography.

This expansion of the field of chromatography was also followed by the expansion of the scope of our journal, reflected in the change of its name to the Journal of Chromatographic Science effective January 1969.

In addition to the introduction of modern liquid chromatography (HPLC), major changes and improvements also took place in the other chromatographic techniques. In gas chromatography, new highly sensitive (and selective) detectors expanded its useful range. At the same time, the use of open-tubular (capillary) columns—which in the early 1960s still found only limited applications—soon started to widen. This was helped by the development of techniques permitting the preparation of glass capillary columns with a stable stationary phase coating. This development finally culminated in 1979 with the introduction of flexible, fused-silica capillary tubing by R.D. Dandeneau and E.H. Zerenner of Hewlett-Packard. Through this invention, open-tubular columns replaced in a short time the conventional packed columns in most applications.

In 1964, J.C. Moore of Dow Chemical Co. introduced hydrophobic polystyrene gels as column packings for the determination of the molecular weight distribution of high-molecular-weight polymers. Within a couple of years, special instruments were also developed for gel-permeation chromatography (GPC), as the use of these polystyrene packings was called. In fact, gel-permeation chromatography and gel filtration are based on the same principles. Eventually, the two variants merged under the name size-exclusion chromatography (SEC), which continues to be an important branch of chromatography.

The 1960s also saw the introduction of a new variant of chromatography in which the mobile phase consisted of a supercritical fluid. This technique may be considered to be halfway between gas and liquid chromatography. In such fluids, the diffusion is faster than in liquids but still slower than in gases; however, separation can be carried out at lower temperatures than with gas chromatography. The possibilities of supercritical fluid chromatography (SFC) were demonstrated almost simultaneously by three independent groups: E. Klesper and A.H. Corwin at Johns Hopkins University, M.N. Myers and J.C. Giddings at the University of Utah, and S.T. Sie and G.W.A. Rijnders at Shell Laboratories in Amsterdam. However, high-performance liquid chromatography soon overshadowed the possible advantages of supercritical fluid chromatography, and thus, no further investigations were carried out at that time. Interest in supercritical fluid chromatography was renewed at the beginning of the 1980s by D.R. Gere at Hewlett-Packard, M. Novotny at Indiana University, and M.L. Lee at Brigham Young University. Based on their work, commercial instruments for supercritical fluid chromatography were soon introduced. For a time, enthusiastic supporters of the technique even predicted that it would revolutionize analytical separations. This did not materialize, but supercritical fluid chromatography is still alive today, although for limited applications only.

All of this development occurred in the lifetime of the present generation, and most of the important contributors to the evolution of chromatography in the last 4 decades are still among us. Their activities shaped the way chromatography is carried out today.

The last decade of the 20th Century saw the growth of two new variants of chromatography: capillary electrophoresis and capillary electrochromatography. Actually, neither technique is new; electrophoresis was originally developed by A. Tiselius at Uppsala University in the 1930s, and the use of electroosmosis to generate the flow of mobile phase in liquid chromatography was proposed 26 years ago by V. Pretorius of the University of Pretoria. The new versions were made possible by the introduction of fused-silica capillary columns. At present, both techniques are creating a lot of excitement, mainly in biochemistry, and this can be attested to just by glancing through the program of this year’s Pittsburgh Conference.

In the 100 years since its inception, Tswett’s original idea grew beyond the inventor’s wildest dream, becoming the most widely used laboratory separation technique. However, chromatography is still continuously growing; its applications widen and newer and newer variants are introduced. In the past two decades, its impact in biochemistry has already started to be felt, and this evolution will definitely be more pronounced in the decades to come. Thus, while chromatography has been the separation technique of the 20th Century, it is definitely also—to cite the slogan of PITTCON 2000—the “science for the 21st Century”.

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