OPTIMAL MEMBRANE CHOICE FOR MICRODIALYSIS SAMPLING OF OLIGOSACCHARIDES

An analytical methodology based on microdialysis sampling, high-perfor mance anion-exchange chromatography and integrated pulsed electrochemi cal detection for the monitoring of oligosaccharides in bioprocesses i s presented. Amylopectin and model maltooligosaccharide standards; glu cose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose and maltoheptaose were used to demonstrate its versatility in view to sampling in enzymatic bioprocesses. The performance and characteristi cs of membranes with the same cut-off ranging between 3 and 100 kDa, w ere evaluated with respect to their extraction fraction (EF), permeabi lity factors, temperature stability and protein (enzyme) interaction. All investigated membranes showed some non-specific interaction with e nzymes. The EF and non-specific membrane-enzyme interactions were high er for the polysulfone membranes compared with the polyamide and polye thersulfone membranes. For all saccharides, the EF was independent of the concentration even for a 250-fold change in concentration. The EF and morphology of the membranes in their dehydrated state, as observed using scanning electron microscopy did not show any significant diffe rence between membranes exposed to a 90 degrees C temperature for 3 an d 24 h indicating their applicability to the study of high temperature bioprocesses. (C) 1998 Elsevier Science B.V.