Synergi Max

Figure 3.11 Influence of gradient duration, Synergi MAX RP 20x4 mm, 2 urn, (a) gradient duration 2 min, (b) 5 min, (c) 10 min.

Symmetry Shield Aqua Zorbax Extend Synergi MAX RP... 

In general, one can be sure that the hydrophobidty of the stationary phase will play the major role, no matter what the analyte is. If the analyte bears basic functional groups, then the silanol activity will surely affect the retention. However, if the analyte does not contain basic functions, then the silanol activity is not very important see also Chapter 2.1.1. The same is true for the polar selectivity. The similarities and differences of stationary phases depend upon the nature of the analytes. For example, the stationary phases Hypersil Elite Cjg, 89, and Synergi MAX RP, 78, are practically identical with respect to hydrophobicity and polar selectivity, but the silanol activity at neutral pH is much lower for the Hypersil Elite Cjg column. Therefore, we would expect very similar separations on both columns if the silanol activity does not play a significant role, but more different separations if the opposite is true. On the other hand, if one is working on a new separation and would like to efficiently exploit the selectivity differences of different columns in an automated method development scheme, then the selectivity charts presented here will certainly be useful in the selection of columns of different selectivity properties. 

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