Patent ID: 7351334

Claim:
A multiple channel liquid chromatographic system, comprising: at least two syringe pumps for pumping solvent in said system wherein each of said at least two syringe pumps includes a piston and a cylinder; a moving frame attached to at least two pistons of said two syringe pumps, wherein movement of each of the pistons with respect to a corresponding cylinder of said syringe pumps is carried out by the moving frame. at least one time-proportioning electronically controllable liquid gradient switching valve; a first mixing means; a second mixing means; said second mixing means being a pump cylinder with an offset inlet that forms eddy currents in the pump cylinder; the first mixing means residing in a fluid flow path between the at least one time-proportioning electronically controllable liquid gradient switching valve and the said at least one of said at least two syringe pumps inlet and the second mixing means resides in the cylinder of the at least one of said at least two syringe pumps downstream of the inlet of the at least one time-proportioning electronically controllable liquid gradient switching valve; wherein the fluid flow path between the said at least one time-proportioning electronically controllable liquid gradient switching valve and the at least one of said at least two syringe pumps inlet is a flow passageway sized to produce formation of elongated streams of first and second solvents with mixing in the said passageway, which in combination with mixing caused by eddy currents in the pump cylinder makes each step of the gradient sufficiently flat and reproducible for a desired set of chromatographic separation processes.