Dynamically-coated capillaries allow for capillary electrophoretic resolution of transferrin sialoforms via direct analysis of human serum

Transferrin sialoforms with fewer than three sialic acid residues (carbohydrate deficient transferrin; CDT) have been implicated as a marker of certain liver pathologies. Transferrin sialoforms in human sera from alcoholic and non-alcoholic patients was analyzed by capillary electrophoresis (CE) using diaminobutane (DAB) to dynamically-coat the capillary wall to minimize protein-wall interactions. Using a DAB concentration of 3 mM, transferrin sialoforms were adequately resolved to allow for direct detection of CDT without extensive treatment of the sera. Serum immunoglobulins, which migrated close to the CDT region, were removed via subtraction with protein A, enhancing the detection of CDT. The reproducibility of sialoform separation in dynamically-coated capillaries was found to be acceptable with run-to-run relative standard deviation values of 0.15% for a sample on a given day and 0.29+/-0.06% for four samples day-to-day. These results suggest that dynamic-coating approaches may provide a simple alternative to the use of covalently-coated capillaries for the CE separation of complex samples.