Microdialysis—a membrane based sampling technique for quantitative determination of proteins

Microdialysis has been coupled on-line to microbore liquid chromatography for sampling and separation of proteins. The performance of 7 different dialysis membranes was investigated in terms of stability, ultrafiltration effects, perfusion liquid composition andin vitro sampling.The relative recovery (dialysate extraction fraction) was determined for cytochromec, insulin, lysozyme and ribonuclease A in the presence of 1 mg mL⁻¹ of human serum albumin (HSA) typically ranged between 10–30% The relative recovery was increased by 15–20% by using α-cyclodextrin.Polysulfone membranes were found to give the best relative recovery regardless of the protein structure. Sampling from cell samples did not have and influence on the dialysis perfomance proving the good biocompatible characteristics of these membranes.