An auto-injection system provides high throughput screening of fluidic samples. A sample injection valve has a first position which applies a reduced pressure to a sample sipper tube for aspirating a fluidic sample into the sample sipper tube, and a second position which delivers the fluidic sample to a sample supply loop. A column control valve has a first position which delivers the fluidic sample from the sample supply loop to a sample chromatography column, and a second position which reverses direction of fluid flow through the sample chromatography column to deliver the fluidic sample to a sample analyzer. A wash control valve has a first position which supplies a wash buffer solution to the sample chromatography column in a forward fluid flow direction, and a second position which supplies elution solvent to flush the sample supply loop.