Technical‎ > ‎

Background and Methods

  • The first studied spiral rotor was composed of eight  plates each with a single spiral groove winding clockwise from 2.4 to 7.5 cm from the center.   The single spiral channel is 2.0-mm deep, 2.6-mm wide and with a 4-mm pitch throughout. The later developed mixer-settler plate has 4 inter-weaved spirals per place with radial flow channels connecting from the inner end of one spiral out to the periphery, underneath to the beginning of the next channel.  At the end of the flow channel on the plate there is a hole transferring the flow to the next plate through the Viton sheet. In the STS the tubing is wound in the frame in 4 spirals per layer.  Therefore the spiral direction is the same CW from center out.
  • The planetary centrifuge is set for either CW or CCW revolution and the lower (heavy) mobile phase is pumped into the inner terminal of the rotor or the upper (light) phase is pumped through the outer end during the elution.  The revolution of the planet centrifuge was set at 800 rpm for these runs. The mobile phase delivery of 2 ml/min was used for the spiral disk and 1 ml/min was used for the STS.
  • In these rotors the inner end is located on the top and the outer end is at the bottom.  See diagram in next column>
Diagram of spiral orientation in the spiral disk and STS rotors
  • The inner and outer ends of the right-handed spiral flow channel become head or tail in terms of distribution of the phases, depending on the rotor direction which is the same as the centrifuge revolution in the type-J synchronous planetary centrifuge. A straightforward way to determine the head and tail of a coil is to have the coil empty and immerse each end of the in and out-flow tubing in water and centrifuge in CW or CCW direction. The end where bubbles come out is the head whereas the tail end is sucking up the liquid.
  • For development of methods for separation of a compound, its partition coefficient in various solvent systems should be determined to select the best conditions.  The suitability of the solvent system is determined by the stationary phase retention measurement.  The SF is given for various solvent systems tested at CC Biotech.   In Table I this was determined in the spiral disk CCC and in Table II are results of using the STS.  Generally, at the same flow rate the STS has the higher SF.