ABOUT CPC

The Basis of CPC

Centrifugal Partition Chromatography (CPC) is a support-free, preparative liquid–liquid chromatographic technique in which separation is governed by partitioning between two immiscible phases of a biphasic solvent system; no solid stationary phase is used. One phase is retained as the stationary phase within a series of interconnected chambers (cells) housed in a rotating rotor, while the other phase is pumped through as the mobile phase (Figure 1). The centrifugal field holds the stationary phase in the rotor as the mobile phase flows through the cells, creating repeated liquid–liquid contact and mass transfer.

CPC can be operated in either descending or ascending mode by switching the flow direction using a valve: in descending mode the denser phase is used as the mobile phase, whereas in ascending mode the less dense phase serves as the mobile phase (Figure 1A, B). After sample injection, analytes distribute between the stationary and mobile phases according to their liquid–liquid partition (distribution) coefficient, Kd, commonly defined as the ratio of the solute concentration in the stationary phase to that in the mobile phase. Consequently, separation in CPC arises from differences in Kd among sample components, leading to differential retention and elution with the mobile phase.

Figure 1: The operational principles of CPC — Figure 1:
The operational principles of CPC. A) A schematic representation of a CPC rotor and a CPC cell operating in ascending mode: the lower (denser) phase (blue) is immobilized inside the cell due to the strong centrifugal force and functions as the stationary phase, while the upper (lighter) phase (grey) is pumped through it against the centrifugal field (percolation). B) In descending mode, the roles of the phases and the direction of the flow are reversed.

Improved Design Offers Throughput Advantages

The cylindrical chamber design of CPC cells enhances stationary phase retention by optimizing the distribution of centrifugal force and improving phase stability during separation. Large bore cylinders are easy to manufacture and provide linear scalability thanks to their unique, patented dimensions and architecture. The individual extraction cells are scaled in a way that performance is not impacted, allowing scaling from 10 to 100 millimeters without loss of efficiency and enabling flow increases from milliliters per minute to multiple liters per minute.

PEEK plugs provide enhanced, stable droplet dispersion of the mobile phase into the stationary phase. The collection plug increases solvent retention, improving loading capacity and chromatographic resolution for the same column size by approximately 20 percent.

Other advantages of our cell design include:

Direct and easy scalability between the portfolio members.
Accessible cell and rotor environment for easy maintenance and cleaning.
Tailor-made cleaning procedure (CIP) for convenience.
Reduced eluent back-mixing.

Separation

During separation, elution refers to the process of selectively washing the solutes from the stationary phase as the mobile phase flows through, thereby facilitating their separation based on their partition coefficients. Conversely, extrusion is a forced displacement step in which the stationary phase is pumped out of the rotor, carrying with it solutes retained in that phase; it is commonly used at the end of a run to recover late-eluting or strongly retained compounds.

The resulting chromatogram provides a visual representation of the separation process, displaying peaks that correspond to the different components — meaning the Compound(s) of Interest (CoI, CoIs) and contaminants in the sample — based on their respective retention times and concentrations as a function of time.

Figure 2: The separation mechanism in CPC: partitioning and partition coefficient (Kd). The determination of Kd is performed using the shake-flask method (left). The chromatographic elution profile obtained for a three-component mixture is analyzed. The separation occurs according to the partition coefficient (Kd) and can be tracked as a function of time based on the retention volume (right).

Technology Comes to Life in Products

RotaChrom provides comprehensive chromatographic platforms tailored to address unique challenges faced by partners in various industries, including pharmaceuticals, biotechnology, chemistry, agrochemicals, and nutraceuticals. These custom-made platforms are designed to handle a wide range of compounds, ensuring versatility in complex separation needs.

By collaborating closely with partners, RotaChrom optimizes each platform for target compounds and purification requirements. The adaptive and modular design of RotaChrom’s systems allows for flexibility and scalability. The purification platforms can be seamlessly expanded to meet evolving requirements, delivering a future-proof solution that grows alongside the business.