Countercurrent chromatography in analytical chemistry (IUPAC Technical Report)

Abstract

Countercurrent chromatography (CCC) is a generic term covering all forms of liquid-liquid chromatography that use a support-free liquid stationary phase held in place by a simple centrifugal or complex centrifugal force field. Biphasic liquid systems are used with one liquid phase being the stationary phase and the other being the mobile phase. Although initiated almost 30 years ago, CCC lacked reliable columns. This is changing now, and the newly designed centrifuges appearing on the market make excellent CCC columns. This review focuses on the advantages of a liquid stationary phase and addresses the chromatographic theory of CCC. The main difference with classical liquid chromatography (LC) is the variable volume of the stationary phase. There are mainly two different ways to obtain a liquid stationary phase using centrifugal forces, the hydrostatic way and the hydrodynamic way. These two kinds of CCC columns are described and compared. The reported applications of CCC in analytical chemistry and comparison with other separation and enrichment methods show that the technique can be successfully used in the analysis of plants and other natural products, for the separation of biochemicals and pharmaceuticals, for the separation of alkaloids from medical herbs, in food analysis, etc. On the basis of the studies of the last two decades, recommendations are also given for the application of CCC in trace inorganic analysis and in radioanalytical chemistry.

Behavior of Oil–Aqueous Solution Systems in Rotating Coil Column

“…This leads to blocking of the RCC tube and decreasing of S f value. Disadjustment of the theoretical model for the hydrophobic biphasic systems [15] and experimental data at segment III is clearly seen. This feature of the multiphase oil systems could enable to find optimal column rotation speeds to obtain high S f values.…”

“…Then the planetary centrifuge is set to rotate and the mobile phase (oil or diesel) was pumped through the column. Optimal elution mode when the lighter phase is pumped from tail to head was shown for amount of biphasic organic systems [5][6][7][8][9][10][11][12][13][14][15][16]. The acid solution is retained in a hydrodynamic column due to a complex centrifugal field while the mobile oil phase was pumped through the column.…”

“…It should be mentioned that the influence of coil planet centrifuge parameters and operating conditions on the stationary phase retention are rather well studied for two-phase liquid systems used for organic and inorganic separations. A number of papers, describing the influence of the physicochemical parameters of two-phase liquid systems (interfacial tension, polarity of solvents, difference in the densities and viscosities of the phases, time of phase separation, and the length of capillary waves at the phase boundary) on the retention of the stationary phase in a column, have been published [5][6][7][8][9][10][11][12][13][14][15][16]. So far, stationary aqueous phase retention in oil-aqueous solution systems has not been investigated.…”

Glossary of Terms Used in Extraction (IUPAC Recommendations 2016)

“…Note 1: CCC is a continuous dynamic process under steady state conditions in which equilibrium may occur but is not essential [23][24][25]. Note 2: CCC differs from countercurrent distribution (CCD) in that CCD is a discontinuous process based on the attainment of equilibrium prior to phase transfer in a multi-stage apparatus.…”

Dispersed Mobile-Phase Countercurrent Chromatography

“…In droplet countercurrent chromatography (DCCC), the passage of single droplets of mobile phase through a column of stationary phase of comparable diameter facilitates solute distribution [6], but the small diameter of the column renders scaling-up difficult. A range of modifications incorporating centrifugation, such as centrifugal partition chromatography (CPC) and high speed countercurrent chromatography (HSCCC) can speed up separation [3,[7][8][9][10][11][12][13][14][15][16][17], but the use of centrifugation increases the cost of equipment, especially on an industrial scale. In controlled-cycle pulsed liquid-liquid chromatography (CPLC), mixing of upper and lower phases is conducted in columns segmented into a cascade of chambers by horizontal perforated plates, yet equilibration of solutes between the phases still has to be achieved on a discontinuous basis with intervening pauses for phase separation in each transfer cycle [18][19][20].…”