Obituary

Farewell Csaba Horváth

Imre Molnár, Molnar Institute, Berlin, Germany.

Csaba Horváth (Roberto C. Goizueta Professor, Chemical Engineering Department, Yale University, New Haven, Connecticut, USA), the founder of modern HPLC, the pioneer of reversed-phase chromatography died on 13 April 2004 after a series of strokes. He was 74 years old.

The American Chemical Society lists Professor Csaba Horváth developed novel columns types, and one of them, the support- alongside such great scientists as James Watson, Linus Pauling coated open-tubular column (SCOT), was later successfully and Ernest Rutherford, individuals who have contributed commercialized. After receiving his PhD he emigrated to the significantly to the developments of chemistry in the 20th USA, was one year at Harvard and since 1964 has been century. associated with Yale University in New Haven, starting as an Csaba Horváth is widely acknowledged as a pioneer of associate professor in the School of Medicine. In this modern separation science, particularly of high-performance laboratory he started to develop, what later became known as liquid chromatography (HPLC) between the late 1960s and HPLC. In fact it was Csaba Horváth, who first named the early 1980s. During recent decades he made further important technique “High Performance Liquid Chromatography” in a contributions to electrodriven separation techniques, especially lecture at the 1970 Pittsburgh Conference. A year later at a to capillary electrophoresis (CE) and to capillary seminar in Rome, Italy, everybody was talking about “akka- electrochromatography (CEC). pee-ella-chi”, which means HPLC and sounded beautiful also Born in 1930 in Szolnok, Hungary, he graduated in chemical in Italian. engineering from the Technical University of Budapest in Csaba has frequently demonstrated a particular interest in the 1952, where he remained until 1956. Following the revolution philology of words connected to separations, and today many in Hungary he left for West Germany and got a job at well-known terms originate from him, for example pellicular Farbwerke Hoechst AG involving chemical process technology. packings, stratified stationary phases, hetaeric chromatography as In 1961 he returned to academia and started doctoral studies a synonym for ion-pair chromatography using hetaerons in gas chromatography under supervision of István Halász at (“counter-ions”) and multimodal separations. the J.W.Goethe University in Frankfurt am Main. Horváth He developed the so called “pellicular configuration of porous stationary phases”, a temporary solution at the advent of HPLC, when uniform spherical stationary phases of good mechanical strength, and precision-metering-pumps for Csaba has frequently demonstrated a generating low flow-rates at high pressure were not yet particular interest in the philology of words available. He assembled the first high-pressure liquid connected to separations, and today many chromatograph for isocratic elution in 1964, which contained a 1 well-known terms originate from him, for 1 m long, /16 in. o.d. and 1.0 mm i.d. stainless steel column. With Phyllis R. Brown, who he introduced into HPLC, this example pellicular packings, stratified new tool facilitated the separation of nucleic acids and stationary phases, hetaeric chromatography nucleotides in the study of cancer metabolism. as a synonym for ion-pair chromatography Csaba is also well known in the field of enzyme kinetics and using hetaerons (“counter-ions”) and developed enzyme reactors for numerous biomedical applications. multimodal separations. In the mid 1970s Csaba Horváth directed his research www.lcgceurope.com Obituary

Csaba Horváth (centre) pictured with Günther Bonn (left) and Imre Molnár (right). towards fundamental studies on reversed-phase the 1970s and revolutionized life science. Surface silanols chromatography (RPC). He adapted the solvophobic theory enhance the selectivity of HPLC columns under a given set of and developed a universal thermodynamically based model for conditions. Today there are approximately 750 different RP the retention mechanism in RPC. Treating solute retention as a columns available, demonstrating the great popularity of the reversible association of the solute with hydrocarbonaceous technique in pharmaceutical and biotechnological applications, ligands of bonded phases, he was able to describe liquid–solid which were the main driving forces for the rapid development chromatography in a fundamental fashion and established a of RPC. basis for the use of the technique for physicochemical measurements. The theory had a major impact on the separation science community resulting in extraordinarily high RPC revolutionized “normal” phase citation numbers.1 The unexpected success of RPC with UV chromatography, in which silica columns detection resulted from the fact that it is a mechanically robust technique employing siliceous bonded phases, easy to use and non-polar organic eluents were applied because of rapid column regeneration and is selective using a — incompatible with aqueous life science wide variety of mobile phases. samples because of emulsion formation in RPC revolutionized “normal” phase chromatography, in the UV detector cells. which silica columns and non-polar organic eluents were applied — incompatible with aqueous life science samples because of emulsion formation in the UV detector cells. The He calculated and published the effect of secondary application of aqueous mobile phases in RPC made possible the equilibria in RPC, such as the mobile phase pH on the analysis of non-volatile water-soluble molecules, such as retention of ionizable molecules and he also investigated ion- peptides and proteins. pair interactions for changing selectivity in a continuous way in Csaba Horváth and his co-workers found, that retention in RPC. Csaba Horváth returned to the solvophobic theory in RPC is dominated by the lipophobic forces of water in the 1998 and stated that partition and adsorption could both be aqueous mobile phase. The lipophobicity in the eluent is explained well in the frame of the solvophobic theory of RPC, proportional to the amount of water (%A) and can be reduced which meant that the composition of the eluent has a dominant by mixing methanol or acetonitrile with water. Based on this role governing RPC retention and that the ligand chain length theory, C18-modified silica columns, which were needed in has a much smaller effect on selectivity, than the influence from biochemistry and pharmaceutical research, quickly emerged in the mobile phase.

LC•GC Europe, 17(7), 418–421, (2004) Obituary

Figure 1: First separation of amino acids and peptides in reversed-phase chromatography by Csaba Horváth.2

1. Glu 2. Val-Ala 3. Tyr 4. Leu 17 21 5. Phe-Gly-Gly + + 6. Phe 22 7. Phe-Gly 0.08 18 During several decades Horváth concentrated his research in + 8. Trp-Glu 19 9. Trp-Gly HPLC and was one of the first to investigate the highly 10. Gly-Phe 11. Trp-Ala efficient separation of amino acids, peptides (Figure 1) and 12. Trp later proteins, comprising both high-speed analytical methods 13. Gly-Trp 9+10 14. Ala-Phe and preparative separations. 0.06 15. Trp-Tyr Of special interest was the refinement of displacement 27 16. Val-Ala-Ala-Phe 17. Phe-Phe chromatography for preparative separations, a technique 18. Phe-Phe pioneered by the Swedish Nobel Laureate, Arne Tiselius. The 8 19. Phe-Gly-Phe-Gly 20. Trp-Leu technique has recently been applied to enhance sensitivity in 5 11 21. Trp-Phe 0.04 15 20 analytical peptide separations coupled to mass spectrometry 22. Trp-Trp 6 23. Trp-Met-Asp-Phe-NH2 (MS). + 16 24. Unknown Miniaturization and the availability of fused-silica capillaries 7 14 25. Unknown

Absorbance at 200 nm 12 26. Lys-Phe-Ile-Gly-Leu-Met brought about major instrumentation changes in the early 90s 3 27. Phe-Phe-Phe 13 and Csaba immediately started exploring electric field mediated 0.02 28. Phe-Phe-Phe-Phe 23 29. Phe-Phe-Phe-Phe-Phe separations in narrow bore tubings. First, he applied this 2 technique to the analysis of complex carbohydrates in 1 26 24 28 29 collaboration with Andras Guttman, who worked at Beckman 25 Instruments at that time. Later his attention turned to the 4 understanding of the fundamental issues of capillary 0 electrochromatography, a hybrid between µLC and capillary 010203040 electrophoresis (CE). Time (min) His research interests included fundamental and applied studies on CE and capillary electrochromatography (CEC). He pointed out that by running CE at 17 °C, the resolution of ions and from high pressures damaging the biological active optical isomers can be improved by a large factor. Also, because tertiary structure of proteins. the conductivity and viscosity are lower, one can apply a higher In recognition of his fundamental and innovative scientific field, which reduces analysis time. Analysis of various work essential for the development of separation science to a conformers of peptides is also possible by running at less than mature tool, especially in the life sciences, Csaba Horváth was 0 °C. He also continued the development of new adsorbents honoured by numerous awards from all over the world. These for biopolymer separations, theoretical and applied non-linear include: chromatography, high-speed HPLC, and biomacromolecular • Dal Nogare Award (1978) interactions. He was also an expert of “hydrophobic interaction • Anniversary Medal of the All-Union Scientific Committee in chromatography (HIC)” for protein separations. Chromatography of the USSR Academy of Sciences (1979) Csaba was famous for his humour. Before RPC became • M.S. Tswett Chromatography Award (1980) popular, everybody used chromatography with unmodified • Humbold Award of the German Federal Republic (1982) silica and organic mobile phases, that was “normal”. Later in • National Award in Chromatography of the American the 80s, in view of the great popularity of non-polar (reversed) Chemical Society (1983) phases in HPLC, he suggested that the use of “normal” • Chromatography Award of the Eastern Analytical stationary phases should be termed “reversed RPC.” Symposium (1986) The success of HPLC was delayed in protein biochemistry as • Van Slyke Award of the New York Metropolitan Section of conditions had to be selected carefully so as not to destroy the American Association of Clinical Chemists (1992) biological activity. Csaba Horváth tried to calm the fears, and • A.J.P. Martin Gold Award of the (British) Chromatographic in so doing, help the biochemists to cure their “litho-, sidero- Society (1994) and barophobias”, their fears of sharp silica edges, from metal • Halasz Medal (1997) • Michael Wildmer Award of the New Swiss Chemical Society (2000) sponsored by Novartis • “Ehrenkranz of Art and Sciences” of the Austrian Academy of Science (2002) During several decades Horváth • Bergman Medal of the Swedish Chemical Society (June concentrated his research in HPLC and was 2003) one of the first to investigate the highly • National Award of the Hungarian Chemical Society efficient separation of amino acids, (October 2003). Csaba was member of numerous scientific societies in several peptides and later proteins. countries (Hungary, Germany, Sweden, Argentina to name a www.lcgceurope.com Obituary

few). In addition, he was an Unfortunately he died on the day that was selected for the external member of the celebration. Hungarian Academy of Csaba’s students are currently discussing how to honour him Sciences, a member of the with their work. A special issue of Journal of Chromatography is Connecticut Separation being planned, containing review articles on work inspired by Science Council (CSSC) and his achievements. the California Separation We are not only missing an outstanding scientific mentor but Science Society (CSSS). also a dear friend. Although we can not compare with his His 70th birthday was scientific excellence, energy and humour, his students will celebrated at numerous events continue the work they started with him. Csaba will continue in several countries and to to live on in his family, the Csabaites and within the scientific mark the occasion the community worldwide. “Horváth Symposium” was organized at Yale University by May God give you peace, Csaba, our dear friend. his former students in January 2000. To express their References appreciation they gave 1. J. Chromatogr., 125, 129–156 (1976). presentations of their latest 2. J.Chromatogr., 142, 623 (1977). scientific results. The full programme can be found at the www.yale.edu and represents the still evolving fields of separation science initiated by Csaba Horváth. These students form a truly international group, originating from Hungary, Germany, France, Sweden, The Netherlands, Russia, China, Italy, India, Lebanon and the USA. They have created a Yahoo newsgroup with 82 members proudly calling themselves “Csabaites”. Although they were in Csaba’s laboratories at different times, they all know each other because of regular visits, where they enjoyed stimulating discussions and listening to Csaba Horváth’s new visions and ideas. Csaba loved to cook or eat in restaurants with his students. Many interesting scientific discussions were conducted at such occasions and Csaba never got tired of listening to his students’ ideas. He even went to NewYork to pick his students from JFK airport, as he was afraid that some would get lost as many didn’t speak english at all. In one instance, with Ziad el Rassi, Csaba tried to make conversation on the way back to Yale – without any success. Finally he asked Ziad, “Can you cook?” “Cook?” that was the first word Ziad did understand and he answered with a happy “YES”, so communication could start — by a joint cooking in the kitchen, continued with the amazing number of over 20 scientific publications in the years to follow. It has to be remembered that Csaba Horváth was a hard worker. His curiosity for new scientific findings kept him in the laboratory until late at night, weekends included. Unfortunately, his stroke took him away from us surprisingly quickly. He was still trying to work on a scientific paper during his final days in hospital. In February 2004 he was elected to the National Academy of Engineering “For pioneering the concept and reduction to practice of high-pressure liquid chromatography (HPLC) and for leadership in the development of bioanalytical techniques.”

LC•GC Europe, 17(7), 418–421, (2004)