Solvent delivery systems composition gradients

Figure 5.3. An example of the proportioning accuracy of a reciprocating-piston pump in the composition range 0-10% B in 1% increments (A). The influence of the design of the solvent delivery system on gradient shape (B). The Broken line describes the set gradient and the solid line the gradient delivered to the column inlet. The dwell time is marked as tp.

The HPLC analyses were conducted with a Water 600 Pump apparatus. This apparatus was equipped with a quaternary solvent delivery system, a Rheodyne injector with 20qL sample loop and a UV detector Waters 486 Tunable which was fixed at 280 nm. Throughout this study. Alltech Intertsil ODS-5 C18 reversed phase column (150 mm, 4.6 mm, 5qm particle size) was used. The flow rate of the mobile phase was of 1 mL / min and the gradient elution was adapted from (Nakatani et al., 2000 Bouayed et al, 2007). The solvent composition and the gradient elution program are reported in the table 1. 

In GPC instrumentation the pumping system delivers a single eluent throughout the analysis. It may be a single solvent, a blend of solvents, or a solvent plus an additive. See. II.C, but the composition remains constant. Solvent programming, also termed gradient elution, in HPLC requires more eapability from the solvent delivery system to ensure precise flow and repro-dueible solvent eomposition profiles. 

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