Effect of injected solvent

Effect of Injected Solvent. It was eventually determined that the mobile phase injected from the first SEC (i.e., pure THF) affected the separation in the second SEC. This is dreunatically demonstrated in Figure 13 which shows the result of injecting a narrow molecular weight distribution polystyrene sample directly into the second SBC. Mobile phase was of constant composition throughout (63.8% n-heptane in THF). However, the solvent used to dissolve the polystyrene was varied from 0% n-heptane in THF to 50% and plotted on the abscissa versus peak retention time on the ordinate. Peak retention time varied from 915 seconds at 0% n-heptane to 960 seconds at 50%. 

The consequences of this effect of injected solvent are as follows ( ) ... 

Figure 13 Effect of injected solvent composition on polystyrene retention in SBC 2. (Reproduced from Ref. 6. Copyright 1983, American Chemical Society.)...

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