Adsorption of albumin-bound toxins on anion exchange resin: An equilibrium study

Bilirubin and tryptophan are among the albumin-bound toxins that must be removed from blood during liver-failure therapy. Artificial liver support devices currently used in clinical practice remove these types of toxins by means of different processes, that are mainly based on adsorption. In this paper, bilirubin and tryptophan adsorption isotherms on anion exchange resin with different albumin concentrations are presented. The results show that the adsorbed amount of toxin decreases with increasing albumin concentration in the solution. This behaviour has been analyzed by means of an original semi-empirical adsorption model that takes in to account the effect of albumin on toxins adsorption equilibrium. The model highlights that this phenomenon is principally because of the competitive binding of toxin between albumin and sorbent, but, in the case of bilirubin, the reduction in the adsorbed amount of toxin was higher than what can be predicted by considering only this phenomenon. From a different point of view, the experimental results show that the anion exchange resin tested is a suitable sorbent for bilirubin removal, while its adsorption capacity for tryptophan is very low and, therefore, different sorptive media should be considered to remove this compound. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.