Spatially and Temporally Resolved Analysis of Bleeding in a Centrifugal Partition Chromatography Rotor

Abstract

Centrifugal Partition Chromatography (CPC) is a separation technique that utilizes immiscible liquid phases to purify compounds. The selection of solvents in Liquid–Liquid Chromatography offers flexibility and optimization possibilities for specific separation tasks. Understanding the hydrodynamics inside the apparatus is crucial for optimizing a CPC process. The phase retention ratio (Sf) determines the apparatus’s operating point and separation efficiency. However, stationary phase leakage, known as bleeding, complicates the immobilization of this phase. We used a partly transparent single-disc rotor to investigate the time and space dependency of bleeding inside a CPC apparatus, enabling real-time and localized determination of the phase retention ratio. By tracking the retention values over time, we observed the bleeding phenomenon and its progression from the inlet to the rotor outlet. Depending on the phase system used, the CPC was utilizable for a separation task for only 173–500 dimensionless residence times. Systems with a higher stability parameter (as described in the literature) showed a lower bleeding rate and increased stability over time. Accordingly, our results demonstrate the importance of maintaining an optimal ratio of mobile to stationary phase for efficient separation.

Optimizing Chromatographic Separation with Redosing: Effects on Separation Efficiency of a Model System in Centrifugal Partition Chromatography

“…A detailed description of the devices is additionally provided in Table 1. The main element of the experimental setup is the FCPC rotor (66 chambers, Sf max = 0.782, V rotor = 10.4 mL), which is connected to the rest of the plant via two rotary joints [17]. A high-speed camera is placed over the rotor to record the chambers in the viewing windows.…”

“…N theo is the number of theoretical stages, and Sf is the retention value [17]. The partition coefficient K D,i of a target molecule to be separated can be calculated according to Equation (2), with c i,stat and c i,mob being the equilibrium concentration in the stationary and mobile phase.…”

“…This causes the entrainment of drops in the stationary phase and, subsequently, the loss of the stationary phase, again decreasing the separation efficiency. This effect is also referred to as bleeding [16,17].…”

“…Our recent research focuses on counteracting bleeding by redosing the stationary phase [17,26,27]. Therefore, the amount of stationary phase lost during a specific timespan is redosed into the apparatus repeatedly.…”

“…In previous publications, we conducted intensive research on the behavior and properties of different solvent systems of the Arizona series [22,29,30]. Therein, the Arizona N system has been studied most, including, among others, flow regimes and the optimization of the chamber design [17,22,23,30]. Another advantage of the Arizona N system is its straightforward handling, and the ratio between the upper and lower phase (0.7) is comparably similar [28].…”