The History of Counter-current Separation Technology - From CCD to EECCC and Notes on Nomenclature

Overview

  • Counter-current Distribution (CCD) Development
  • DCCC (Droplet CCC)
  • CPC (Centrifugal Partition Chromatography)
  • HSCCC (High Speed CCC)
  • EECCC (Elution Extrusion CCC), a popular operation mode for CPC and HSCCC
  • Advantages of CCC
  

Introduction

Let’s start at the beginning…
In order to understand partition chromatography, one must first understand partitioning (liquid-liquid extraction). Partitioning has three stages:

  1. Mixing - Thoroughly mix the two phases
  2. Settling - Allow the mixture to settle into two phases
  3. Separating - Separate the phases from each other

The physiochemical property that allows compounds to be separated through partitioning is called the Partition coefficient (K). This is defined as the concentration (C) of a compound in the upper phase of a specific specific two-phase solvent system divided by the concentration of the compound in the lower phase of the same two-phase solvent system (C[upper]/C[lower]).

  • Advancements in strumentation are driven by improving partitioning efficiency!

Nomenclature

For historic reasons and due to the lack of harmonization, the "CCC" nomenclature is rather fragmented in the literature. Due to the historic hyphenated spelling of "counter-current", the non-hyphenated spelling of "countercurrent" used today continues to be still abbreviated as "CC" rather than "C". Accordingly, CCC typically stands for "counter[-]current chromatography".

One major stream of "CCC" instrument development led to a wide range of centrifugal partition chromatographs ("CPC"; hydrostatic instruments) and has emphasizse partitioning as its underlying mechanism. At the same time, the name of another line of instruments, generally termed high-speed countercurrent chromatographs ("HSCCC"; hydrodynamic instruments) or variants thereof, has continued to use the original "CCC" term.

Notably, both CPC and HSCCC instruments share the same basic principles of operation and chromatographic theory, as well as user base. Reflecting the shared principles, we have been using the unifying terms "countercurrent separation" ("CS", syn. "CCS") to describe both principal methods.

  • See our review article for more detailed information:
    Pauli GF, Pro S, Friesen JB
    Countercurrent separation of natural products
    Journal of Natural Products 71: 1489–1508 (2008)
    doi: dx.doi.org/10.1021/np800144q
  • An updated review covering the literature 2008-2014 is currently being prepared

 

Counter-current Distribution

In the 1940s Lyman C. Craig invented the first apparatus (besides a separation funnel!) to conduct counter-current partitioning; he called this Counter-current Distribution (CCD). Shown here is an apparatus built by Hecker (Tuebingen, Germany) that allowed manual CCD of samples.
 

Droplet CCC (DCCC)

The concept: One phase drips through the second phase, in ascending (upper phase = mobile) or descending mode (lower phase = mobile).

  • Low flow rate (relies on gravity) makes DCCC a time consuming separation method
  • Drawback: relatively poor mixing leads to reduced separation efficiency
 

Centrifugal Partition Chromatography (CPC)

Basically, CPC is hydrostatic like DCCC, but with improved mixing and more theoretical plates

  • Spinning rotor
  • Centrifugal field vs. gravitational field to hold one phase stationary
  • Still “hydrostatic” separation – constant g-field
  • One axis of gyration
  • Much faster separations than in DCCC (flowrates ca. 100-fold higher, FCPC)

Literature

Murayama, W. et al., J. Chromatogr., 239, 643-649 (1982)

Links

http://www.richardscientific.com/fcpc.htm

 
             
               

High Speed CCC (HSCCC)

  • Yoichiro Ito (NIH, Bethesda, MD) developed planetary, centrifugal CCC
  • “Increases gravity” – improves mixing - created hydrodynamic equilibrium
  • Theoretically thousands (up to 70,000 per hour) partitioning/chromatographic steps
  • Mixing, Settling, Separating

To help understand how this works…

  • HSCCC Movie...coming soon
  • note – planetary motion of coils, pink is mixing zone
      
           
     
             

Elution Extrusion CCC (EECCC)

  • Co-developed by Alain Berthod (Univ Lyon, Villeurbanne, France) et al.
  • Technique utilizing modern HSCCC
  • Concept: Extrude "column" after certain K value
    • Allows high resolution of significantly larger range of K values in a given time

Advantages of CCC

  • Quick (high throughput in preparative separation)
  • Inexpensive (only solvent costs, which still are significantly lower than in HPLC)
  • Gentle and versatile, for separation of varied compounds, with less chance of decomposition
  • Able to range from milligrams to tens of grams on the same instrument
  • Able to switch between normal and reversed-phase at will
  • Free of irreversible adsorption to a solid support (100% recovery of sample)

Literature

Armbruster, J. et al. Journal of Liquid Chromatography and Related Technology 24, 1827-1840 (2001).

Alvi, K. A. Journal of Liquid Chromatography & Related Technologies 24, 1765-1773 (2001).