On-line Sample Manipulation in Capillary During Electrophoretic Separation

Hydrodynamic pressure is applied together with high voltage to achieve rapid capillary electrophoretic separation of amino acids. Moreover pressure is used to force the undesirable solvent from the sample zone out of the capillary. Determination of the branched-chain amino acids (BCAAs) valine, isoleucine, and leucine in human blood plasma is completed by capillary electrophoresis (CE) with contactless conductivity detection in optimized background electrolyte 3.2 M acetic acid in 20% v/v methanol, pH 2.0. The achieved separation time was 125 s when using a capillary with an effective length of 14.7 cm, electric field intensity of 0.96 kV/cm and simultaneous application of a hydrodynamic pressure of 50 mbar. It followed from the performed tests that the plasmatic levels of BCAAs attain a maximum 60 minutes after intravenous application of an infusion of BCAAs.