High Speed Liquid Chromatography

Abstract

This review deals with the most rapidly expanding form of chromatographic analysis variously known as high speed, high performance, high pressure, or high efficiency liquid chromatography. The technique which we shall denote by high speed liquid chromatography (HSLC) has arisen from a marriage of classical liquid chromatography and modern gas chromatography. The beginnings of HSLC may be traced to a statement in the classic paper of Martin & Synge (I) of 1941, in which they wrote: Thus the smallest HETP should be obtainable by using very small particles and a high pressure differ­ ence across the length of the column. Until the late 1960s this recipe for HSLC was l<irgely ignored, and typical separations by liquid chromatography took several hours or even days. As is well known, Martin and Synge's pre­ diction of gas chromatography was not followed up until about ten years later (2-4) but from that time onwards it developed rapidly. It was eagerly taken up by petroleum and oil chemists, and the theory of the method developed rapidly in the hands of chemical engineers and physical chemists (5). By 1960 it was recognized by the majority of practicing gas chromatographers that the retention of a solute relative to the unretained air was determined by thermodynamic considerations and that the dispersion of a peak as it moved along a column was largely determined by kinetic factors, in which diffusion played an important role. . The theory of chromatography in the context of gas chromatography was greatly clarified by the work of Giddings, and particularly by the publication in 1965 of his book, Dynamics of Chromatography Part 1 (6). However, it was plain about this time that the theory developed and tested for gas chromatog­ raphy could equally well be applied to liquid chromatography with only minor modifications (7, 8). T ndeed this had been realized in 1960 by Hamilton (9) who applied gas chromatographic theory in an attempt to improve the speed and efficiency of the analysis of amino acids using ion exchange (10). It is unfortunate that this work, like that of Martin & Synge ( 1), was largely