Patent ID: 7862716

Claim:
An HPLC flow system, comprising a separation column; a detector; and means connecting the outlet end of the separation column with the detector; a syringe; an injector with a sample reservoir; a sample accumulation loop; a guard column; and means connecting the syringe to the accumulation loop, to one end of the guard column, and to the injector, sample reservoir and waste; and a mobile phase reservoir; a high pressure pump; and valve means operable: in a first operative position to define a first flow schematic serially connecting the injector and sample reservoir, accumulation loop, and syringe, whereby powered syringe intake draws the sample into the accumulation loop; and in a second operative position to define a second flow schematic serially connecting the pump, accumulation loop, guard column, separation column, detector, and the injector to waste, whereby pump operation advances the mobile phase and sample in one direction serially through these components; and in the first operative position again to define a third flow schematic, whereby pump operation advances the mobile phase in the same direction through the separation column and detector, while advancing the mobile phase in the reverse direction through the guard column for back flushing it.