EFFECT OF LIQUID-PHASE COMPOSITION ON THE HENRY'S CONSTANTS OF VALINE, ISOLEUCINE, AND LEUCINE IN A CAPCELL-PACK C₁₈ CHROMATOGRAPHY

Abstract

The adsorption equilibria of valine, isoleucine, and leucine in a Capcell-Pak C₁₈ chromatography were measured using a frontal analysis method. This task was carried out at room temperature while varying the methanol content in liquid phase from 5% (v/v) to 50% (v/v). Based on the resultant adsorption data, the Henry's constant, which is the ratio of solid-phase and liquid-phase concentrations at equilibrium, was determined for each amino acid and each liquid-phase composition. It was found that the Henry's constant of valine was markedly different from those of isoleucine and leucine. In addition, the liquid-phase composition had a significant effect on the Henry's constant of each amino acid. To describe such effect mathematically, several models were tested and their performances were compared. It was confirmed that the Abel model was the most accurate in predicting the Henry's constant of each amino acid as a function of the liquid-phase composition. The adsorption equilibrium data and the model parameters reported in this study will be useful in the stage of optimizing a chromatographic process for separation of valine from isoleucine and leucine.

ACKNOWLEDGMENT

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (Grant number 2012R1A2A2A01019790). Also, it was partially supported by the Manpower Development Program for Energy & Resources supported by the Ministry of Knowledge and Economy (MKE), Republic of Korea.

Notes

^a , where q ^cal and q ^exp are the calculated solid-phase concentration and the experimentally measured solid-phase concentration, respectively; n is the number of data points (n = 5); and p is the number of model parameters fitted (p = 1).

^a , where H ^cal and H ^exp are the model-predicted Henry's constant and the experimental-based Henry's constant, respectively; n is the number of data points (n = 7); and p is the number of model parameters fitted (p = 2).

^a , where H ^cal and H ^exp are the model-predicted Henry's constant and the experimental-based Henry's constant, respectively; n is the number of data points (n = 7); and p is the number of model parameters fitted (p = 3).