Application of a high-pressure electro-osmotic pump using nanometer silica in capillary liquid chromatography

A novel designed electro-osmotic pump (EOP) with simple structure was assembled using three 20 cm x 530 mum i.d. fused-silica capillaries packed with 20 +/- 5 nm silica grains for capillary liquid chromatography. It was found that the pump could generate pressures over 20 MPa and several muL/min flow rate for most of the liquids being delivered with the applied voltage less than 10 kV. By increasing the pressure, decreasing the applied voltage and the electrical current, the thermodynamic efficiency was about 1-4%. A practical application of the EOP in a 20 cm x 150 mum i.d. 3 mum C-18 fused-silica analytical capillary column demonstrated the applicability of the pump. (C) 2004 Elsevier B.V. All rights reserved.