U HPLC and Mass Spectrometry

Pump type and mixing volume To some degree, all modern (U)HPLC pumps allow you to realize an overall GDV of 250 )il or less - getting much below 100 pi of GDV, however, is still a major challenge. Due to their operation principle, high-pressure gradient (HPG)pumps have an inherent advantage with respect to GDV 

The GDV discussion is a particularly difficult one for pumps still having membrane-based pulsation dampeners. In this case, the GDV also depends on the system pressure, and by that on the separation flow rate [77]. While all major manufacturers of modern UHPLC pumps nowadays have established electronic control mechanisms in their high-end and most middle-class instruments that allow a virtually ripple-free flow delivery without dampeners, some older pumps or simpler entry-level models still have to rely on mechanical dampening. It would not be appropriate in general to use such pump types together with MS detection. 

Minimize the GDV of your LC system - it wiii heip to remarkabiy reduce anai-ysis time. HPG pumps are of inherent advantage here. 

GDV means more than the pump mixer. Assess aii voiumes from the gradient formation point to the coiumn head for minimum GDV, but without sacrificing mixing performance. 

Contributions of connection tubing to the GDV can typicaiiy be negiected in case of anaiyticai scaie LC separations. 

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