Influence of geometry and equilibrium chemistry on relative recovery during enhanced microdialysis

Cyclodextrin-mediated enhanced relative recovery (RR) during microdialysis sampling was studied by varying probe membrane length and material. Different analyte/cyclodextrin complexes that had formation constants ranging between logKf of 0.92 and 2.6 were studied. Enhanced RR was significantly greater when logKf was >2.0. As membrane length increased, the enhanced RR for all compounds increased. Enhanced RR values reached a plateau level at low perfusion fluid flow rates with 10mm microdialysis membranes. Polycarbonate/polyether membranes exhibited significantly higher enhanced RR than polyethersulfone membranes. These studies suggest that a combination of chemical and membrane properties must be considered in order to achieve significant enhanced RR during microdialysis sampling.