Interaction of heparin and tetraarginine in capillary electrophoresis: Implication for analytical applications

Interactions between heparin and tetraarginine in an acidic background electrolyte were investigated in capillary electrophoresis. The results showed that tetraarginine and heparin form a stable complex that migrates toward the anode immediately after coming into contact. When a zone of tetraarginine at a mg/mL concentration level passes through a zone of heparin at a μg/mL concentration level, tetraarginine is gradually removed by the formation of the complex that migrates in the opposite direction, thereby decreasing the tetraarginine peak area. The variation of the tetraarginine peak area as a function of the unfractionated heparin concentration was linear within the range 2-20 μg/mL, which enables us to detect and determine heparin concentrations undetectable with a UV detector. The same behavior was confirmed for low molecular weight heparin.