Separation by High-Speed Countercurrent Chromatography

Modern high-speed countercurrent chromatography (HSCC) has arisen only over the last 15 or so years and offers the natural product chemist a new separation tool with many unique advantages. It is inherently the mildest form of chromatography with no solid support and hence no chance of loss of substrate by binding to the column. The only media encountered by the sample are solvent and Teflon tubing. The former is common to all forms of chromatography and the latter to most. It is true that the solvent systems have more components than many other forms of chromatography, but these can be chosen from the most nonreactive and innocuous solvents. Hence the chromatographer is virtually assured of near 100% recovery of sample from a chromatography. The number of two-phase systems that can be employed is limited only by the imagination of the chromatographer, and the systems can be explored by any of several simple tests, prior to a preparative separation, to ensure success. Two similar compounds of almost identical polarity can have surprisingly different partition coefficients in a specific two-phase system resulting in baseline separation by countercurrent chromatography.