Syringe pump system for pulse-free metering and precise mixing in hplc uhplc, micro-hplc and nano-hplc

Abstract

The invention describes a high-pressure syringe pump system for use in the field of HPLC, UHPLC, micro-HPLC and nano-HPLC in gradient operation. The different solvents are compressed independently by passive non-return valves, the solvent combination does not take place until at an identical pressure, and the target pressure for the initialization is achieved by a control setting with a higher delivery capacity, in which the compressibility is also taken into consideration. The changing of solvents and the flushing of the pump heads take place by way of separate inlets and outlets in the throughflow via an active multiple-position high-pressure valve which can also close the pump head and can open it via the passive non-return valve. The regulating unit and the drive motor which also serves as force sensor detect compressibility, air inclusions and leaks. Depending on the embodiment, the syringe pump heads are stabilized thermally.

1 . A syringe pump system for HPLC with at least two solvents, having two mutually independent syringe pumps coupled to form a binary system and each having a pump cylinder that is connected with a multi-position valve by an outlet connection line that is provided with a respective passive pump outlet valve, a respective intake line, and a respective washing outlet line, each multi position valve having a further outlet line that opens into a common outlet line at a manifold fitting, the pressure required for chromatographic analysis, for each of the solvents, being built up separately in the respective pump cylinders, by the respective pump pistons and on the basis of the respective passive pump outlet valve. 
     
     
         2 . The syringe pump system according to  claim 1 , wherein each syringe pump has a motor as a drive for the respective pump piston and as a force sensor for compression of the respective solvent. 
     
     
         3 . The syringe pump system according to  claim 2 , wherein in addition a controller is provided, and that the motor and the controller detect air inclusions, the compressibility of the solvent, and leaks. 
     
     
         4 . A method of pulse-free feeding and precise mixing of at least two solvents for HPLC in gradient operation, using a syringe pump system having two mutually independent syringe pumps each having respective pump cylinders connected with respective multi-position valves, flushed and closed by this valve by lines separate from one another, and operated by a passive pump outlet valve so that the pressure buildup required for gradient operation takes place in the respective pump cylinders and mixing of the solvents in a manifold only takes place when the same pressure has been reached. 
     
     
         5 . The method according to  claim 4 , wherein the pressure in the syringe pumps builds up synchronously. 
     
     
         6 . The method according to  claim 4 , wherein the pistons of the syringe pumps are driven by respective motors whose motor force is measured separately, and that the solvent pressure in the pump cylinders is essentially proportional to the motor force. 
     
     
         7 . The method according to  claim 4 , wherein the syringe pumps are re-initialized for each individual HPLC analysis, and thereby the same starting conditions exist for the syringe pumps and chromatographic analysis. 
     
     
         8 . Use of the syringe pump system according to  claim 1  in the field of HPLC, UHPLC, as well as nano-HPLC and micro-HPLC. 
     
     
         9 . Use of the syringe pump system according to  claim 1  for gradient elution, isocratic elution, and in continuous flow mode.