Applications of Liquid-Liquid Chromatography Instrumentation for Laboratory Preparative & Process Chemistry

Liquid-Liquid Chromatography instrumentation (L-LC), also referred to as Counter Current Chromatography (CCC), and Centrifugal Partition Chromatography (CPC), design has been instigated and, championed largely by Academics at University and Research Institutes in USA, Japan, Europe and China. To date instrumental L-LC has not been universally adopted by chromatographers in many commercial sectors. Discussed is a
scientific treatise from a commercial viewpoint, of usage and design advantages and disadvantages of instrumental L-LC.

INTRODUCTION
There are very many fundamentally different modes of LLC instrumentation design. The two major design modes in present use are planetary centrifuges (usually referred to as CCC, HSCCC or HPCCC) and sun centrifuges (often referred to as sun or droplet CPC), Recently the International CCC Committee voted to define planetary CCC as hydrodynamic CCC, and sun or droplet CPC as hydrostatic CCC, whilst acknowledging that both are Centrifugal Partition Chromatographs (CPC). The industry wide use of CCC nomenclature has lead to much confusion in the mode of operation, as to non LLC chromatographers; Counter Current modes would involve two liquids moving in different directions. With L-LC/CCC despite the fact they can readily be used with liquids moving in two opposing directions, in reality over 99.9+% of usage cases, only one phase is stationary and one phase is mobile. For this reason we have chosen to refer to this science as L-LC rather than CCC or CPC. In this publication we will refer to planetary CCC, HSCCC and HPCCC as hydrodynamic L-LC and sun or droplet CPC as hydrostatic L-LC. Solid Liquid Chromatography (SLC) techniques would include Open Tubular, Flash, Medium Pressure Liquid Chromatography (MPLC) and High Pressure (Performance) Liquid Chromatography (HPLC). In S-LC one phase is stationary and one phase mobile. The stationary phase is often an immobilised liquid, which has been immobilised by bonding to a solid substrate. Liquid-Liquid Chromatography is therefore in many ways directly analogous to Solid Liquid Chromatography. The main difference between L-LC and S-LC in many cases is L-LC maintains one of the pair of immiscible liquids stationary, through its physical mechanical/electrical instrument design, rather than adsorption onto a solid particle. Why then is not L-LC the equal scientifically/commercially of S-LC?