Automated sample introduction for an imaged capillary isoelectric focusing instrument via high-performance liquid chromatography sampling devices.

Sample introduction of an imaged capillary isoelectric focusing (cIEF) instrument is fully automated by using commercially available high-performance liquid chromatography (HPLC) injection valves and autosamplers. Sample carryover can be controlled to under 1% when the valve and separation column are washed for 1 min between sample runs. The standard deviation of peak areas for 20 injections is 3.5%, which includes deviations created by the absorption imaging detector and the isoelectric focusing process inside the 75 microm I.D. column. Sample throughput is up to 10 samples per hour. The instrument has been applied to fast analysis of many proteins including monoclonal antibodies.