Countercurrent Liquid Chromatography

Figure 1 Two basic CCC systems. (A) Hydrostatic equilibrium system. (B) Hydrodynamic equilibrium system.

materials present in the coil that are either heavier or lighter than the suspending medium are driven toward one end of the coil. This end is conventionally called the head; the other end is called the tail.

Owing to the effect of this Archimedean screw force, the mobile phase introduced through the head end of the coil immediately interacts with the stationary phase to establish a hydrodynamic equilibrium. The two solvent phases are distributed fairly evenly in each helical turn where they are vigorously mixed by the rotation of the coil. After the entire coil reaches this equilibrium state, the mobile phase only displaces the same phase, leaving a large amount of the other phase stationary in the coil. Consequently, solutes introduced through the inlet of the coil are efficiently separated and eluted out in the order of their partition coefficients.

Each basic CCC system described above has its own merits. The hydrostatic system gives a stable retention of the stationary phase whereas the hy-drodynamic system yields a higher partition efficiency by vigorous mixing of the two phases with the rotation of the coil. Several efficient CCC systems have been developed from each basic system.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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