UNTRADITIONAL APPLICATIONS OF COUNTERCURRENT CHROMATOGRAPHY

ABSTRACT

Rotating coiled columns (RCC) have been traditionally applied to the separation and purification of organic solutes by countercurrent chromatography (CCC). The technique is based on the retention of one phase (stationary) of a two-phase solvent system in a rotating column without solid support under the action of centrifugal forces, while the other liquid phase (mobile) is being continuously pumped through. Solutes are subjected to a partition process between two phases and eluted in order of their partition coefficients. Within the last several years, some fundamentals and methods of inorganic separations by CCC in two-phase liquid systems, with different solvents and extracting reagents, have been developed. Procedures for the group pre-separation of rare earth and some rare (Zr, Hf, Nb, Ta) elements from multi-component matrices were proposed. The application of CCC to the purification and analysis of salt solutions has also been investigated. Recently, it has been shown that rotating columns can be used for the separation of both solutes and particles, not only in liquid–liquid systems but in liquid–solid–liquid and liquid–solid systems as well. Procedures for the direct extraction of polynuclear aromatic hydrocarbons from a sewage sludge medium, and continuous fractionation of trace elements in soils were developed; suspensions and powdered solid samples being applied as the stationary phase in the column. It has been demonstrated, that RCC can be successfully used for the fractionation of micro particles. There is no stationary phase in this case. The centrifugal forces acting on RCC provide different migration speeds of the suspended sample components in one carrier fluid.

Keywords:

• Rotating coiled columns
• Separation
• Purification
• Fractionation
• Leaching
• Rare and rare earth elements
• Heavy metals
• Polynuclear aromatic hydrocarbons
• Sewage sludge
• Soil

Acknowledgments