Liquid Chromatography - The Syringe Pump
With careful design and exacting construction these types of valve can be extremely efficient. In practice, to ensure the most effective performance, a single non-return valve assembly usually contains two non-return ball valves connected in series as shown in figure 5.
The Syringe Pump
The syringe pump is a large, electrically operated simulation of a hypodermic syringe. Although used in the early days of LC renaissance, it is rarely used today as, due to its design, it can provide only a limited pressure and the volume of mobile phase available for use is restricted to the pump volume. Unless the separation is stopped while the pump is refilled and the development subsequently continued, the pump can only elute solutes that have retention volumes equal or less than the pump capacity. A diagram of a syringe pump is shown in figure 6.
Courtesy of the Perkin Elmer Corporation
Figure 6. The Syringe Pump