Countercurrent Chromatography (CCC) was originally developed through the work of Dr. Yoichiro Ito at NIH in the early 1970s.

In general, CCC is a fully scalable separation technique in which components are separated as a result of repeated partitioning between two liquid phases of a biphasic solvent system. CCC is therefore a liquid-liquid technique, meaning both the mobile and stationary phases are liquids. This feature allows CCC to avoid many of the problems associated with solid support chromatography, while providing versatile selectivity over a full range of polarities and compound classes.

One of the major developmental challenges of CCC was the retention of the liquid stationary phase within the system, while still being able to pump a mobile phase through it. The stationary phase in solid phase chromatography is held in place by simply packing it into an inert cylinder. If packed properly, a mobile phase can be pumped through without dislodging the stationary phase. CCC technology on the other hand, requires something fundamentally different to retain the stationary phase. The original machines relied heavily on gravity to achieve retention; however, modern CCCs use centrifugal forces, which provide much faster separations.

There are two basic types of CCC instruments commonly used today: Type-J and CPC. To mark new standards in high speed and throughput, manufactures have recently coined terms such as HPCCC and FCPC, but all can essentially be classified into the two basic types. The difference between these two types has to do with their core mechanical design, and each has its own set of advantages. However, both provide means for liquid stationary phase retention as well as effectively create many zones of mixing, settling and separation, which progress along the internal liquid path of the systems. These three important steps can be thought of as exactly the same thing that happens with an analyte in a separatory funnel, but repeated up to 250,000 times per hour!

It should be noted that, unlike HPLC or other solid phase techniques, CCC users are not limited by the composition or cost of commercially available columns. Since CCC uses only liquids as the separation medium, the makeup and behavior of the column is completely under the user’s control. Not only can a user essentially “install” a new liquid column quickly and easily, but a variety of operational techniques can be used to capitalize on the dynamic nature of that column. To put it quite simply, CCC can achieve separations that are just not possible using other techniques. Further, a liquid-only column allows for the high loading of crude and difficult to dissolve samples, and provides a gentle environment to prevent the degradation of delicate samples. Also, because of CCC’s full sample/product recovery, even minor constituents can be completely isolated without the threat of irreversible loss from column adsorption. CCC also scales extremely well; methods developed on analytical instruments can be directly applied to larger machines to achieve (semi-)preparative or production scale throughput.

Mechanical problems associated with older CCC instruments have been solved, with the newest generation providing fast, reliable operation, at low noise levels, and long periods between maintenance. Further, the literature and knowledge base has been growing at an accelerated rate, and a once hard-to-find expertise is now becoming a standard tool among separation scientists.