Inline injection pumps

Figure 9-77 illustrates the required valve switching for this technique. In the first step (Fig. 9-77A), the injection loop (5 mL) is filled with the solvent sample. Sample delivery is carried out with a simple isocratic pump at a flow rate of 1.5 mL/min for seven minutes out of a reservoir with a small head pressure, so that the loop is rinsed several times with sample. After loading the loop, the sample is transferred with ultra-high purity water to the concentrator column, in which the anions or cations are retained (Fig. 9-77B). The remaining solvent is rinsed off with ultra-high purity water (flow rate 1.7 mL/min rinse time 10 minutes). Afterwards, the concentrator column is put inline with the analytical separator column. The pre-concentrated ions are then eluted from the concentrator column in opposite directions and separated on the analytical separator...

FIGURE 17,1 Schematic representation of the different flow strategies applied in the spectrophotometric determination of tartaric acid without (a) and with (b through d) inline dialysis unit. S, sample P, pump RC, reaction coil CC, chromatography column C, carrier D, donor stream A, acceptor stream R, reagent E, eluent X., detector vertical arrows indicate injection valves. 

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