MINIATURE FIELD-FLOW FRACTIONATION SYSTEM FOR ANALYSIS OF BLOOD-CELLS

Field-flow fractionation is an analytical tool that has been historica lly used to separate species, ranging from molecules to particles or c ells several micrometers in size. This technology can effect separatio n by size, density, charge, or other physical properties, depending on the configuration of the field-flow system. We have developed a minia ture field-flow system to analyze cell populations in a small, 125-mu m-deep channel 19 cm long. Gravity is used as the primary field to eff ect separation, and cell analysis is performed in <20 min. Erythrocyte s elute as a single peak when diluted blood is fractionated in this sy stem. Analysis of blood samples from several donors (normal controls a nd patients with sickle cell anemia) yields erythrocyte peaks with sli ghtly different mobilities (elution times). Peak mobility does not dir ectly correlate with mean cell volume or other standard erythrocyte pa rameters. Cell density appears to be a key factor in determining cell mobility with this system.