Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS
(CPC), employs a constant gravity fi eld produced by a single axis rotation,
together with rotatory seals for supply of solvent. Separation takes place in
cartridges or disks. CPC with cartridges or disks is a hydrostatic equilibrium
system. If the coil is fi lled with the stationary phase of a biphasic solvent
system and then the other phase is pumped through the coil at a suitable
speed, a point is reached at which no further displacement of the stationary
phase occurs and the apparatus contains approximately 50% of each of the
two phases. Steady pumping-in of mobile phase results in elution of mobile
phase alone. This basic system uses only 50% of the effi cient column space
for actual mixing of the two phases.
A more effective way of using the column space is to rotate the
coil around its central axis while eluting the mobile phase. A hydrodynamic
equilibrium is rapidly established between the two phases and almost 100%
of the column space can be used for their mixing. CCC with rotating coil
instruments is an example of this latter mechanism.
• The planetary motion is produced by engaging a planetary
gear mounted on the column holder axis to an identical stationary
sun gear rigidly fi xed to the centrifuge framework.
• This 1:1 gear coupling produces a particular type of planetary
motion of the column holder, i.e. the holder rotates about
its own axis while revolving around the centrifuge axis at the
same angular velocity (synchronous) in the same direction.
• This planetary motion provides two major functions for performing
CCC separation. The fi rst is a rotary-seal-free elution
system so that the mobile phase is continuously eluted
through the rotating separation column.
• The second and more important function is that it produces
a unique hydrodynamic motion of two solvent phases within
the rotating multilayer coiled column mainly due to the
Archimedean screw effect.
13.3 HSCCC Instrument and Mechanism
Figure 4: High speed counter-current chromatography instrument
When two immiscible solvent phases are introduced in an endclosed
coiled column, the rotation separates the two phases completely
215