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

Microdialysis has been coupled on-line to microbore liquid chromatography f or sampling and separation of proteins. The performance of 7 different dial ysis membranes was investigated in terms of stability, ultrafiltration effe cts, perfusion liquid composition and in vitro sampling. The relative recovery (dialysate extraction fraction) was determined for cy tochrome 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 rel ative recovery was increased by 15-20 % by using alpha-cyclodextrin. Polysulfone membranes were found to give the best relative recovery regardl ess of the protein structure. Sampling from cell samples did not have an in fluence on the dialysis performance proving the good biocompatible characte ristics of these membranes.