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 Ϫ17 °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