Solvent delivery systems degassing

A modern solvent delivery system consists of one or more pumps, solvent reservoirs, and a degassing system. HPLC pumps can be categorized in several ways by flow range, driving mechanism, or blending method. A typical analytical pump has a flow range of 0.001-10 mL/min, which handles comfortably the flow rates required for most analytical work (e.g., 0.5-3 mL/min). Preparative pumps can have a flow range from 30 mL/min up to L/m. 

A modern HPLC solvent delivery system consists of one or more pumps, solvent reservoirs, and a degassing system. Typical requirements of an analytical HPLC pumps are ... 

Fig. 2 shows a sketch of a typical measuring system used in our laboratory. A buffer solution in reservoir (R) containing 7 mM sodium azide as a preservative is pumped through a sintered stainless steel filter (Fx). Air dissolved in the buffer solution is removed by a degasser (DC). The buffer solution is supplied to the column at constant flow rate by a solvent delivery system equipped with a sample injector. Another sintered stainless steel filter (F2)... 

The solvent delivery system comprises a means of degassing, filtering and blending up to four solvents which are then delivered to the top of the column under pressure by a constant flow pmnp. 

Solvent delivery modules are required to deliver a pulse free flow of eluant to the column at flow rates ranging from 0.1 to 10 ml min with a precision of 0.5% or better. The pump must be capable of operating at pressures up to 7000 psi (48.3 MPa) and the system should incorporate a degassing unit to remove dissolved air and other gases from the eluant. 

Figure 10 The primary components of the system shown in Fig. 9 include the control panel (upper left), injection mechanism (upper right), autosampler carousels (mid-level), independently driven dual reciprocating solvent delivery pistons (lower left), and degasser/solvent select module (lower right). 

Solvents used as the mobile phase are contained in solvent reservoirs. In their simplest forms, the reservoirs are glass bottles or flasks into which feed Lines to the pump are inserted. To remove particles from solvents, inline filters are placed on the inlets of the feed lines. Sophisticated mobile phase handling systems available commercially contain specially designed bottles with internal, conically shaped bottoms that allow small solvent volumes to be used. These handling systems also feature three or four valve caps that permit the filtration, storage, and delivery of solvents, and a stopcock for vacuum degassing. 

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