Rapid electrodialytic clean-up of biological samples for high-performance liquid chromatography

A sample clean-up system employing electrodialysis with size-selective and charge-selective membranes is described. When applied to the treatment of 0.5-ml milk samples containing sulfamethazine, the system produced an undiluted, clear solution in 3 min and eliminated the components in untreated milk that caused column fouling and double peaks. In contrast to conventional liquid- and solid-phase extraction procedures, electrodialytic clean-up is readily automated and uses no organic solvents.