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 and in vitro sampling. The relative recovery (dialysate extraction fraction) was determined for cytochrome c, 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 alpha-cyclodextrin. Polysulfone membranes were found to give the best relative recovery regardless of the protein structure. Sampling from cell samples did not have an influence on the dialysis performance proving the good biocompatible characteristics of these membranes.