Figure 7-33. Examples of the effect of 2D elution conditions on the utilization of the 2D separation space in LC x LC separations of phenolic acids and flavones. The separation in Panel (A) is obtained when the same 2D gradient is used throughout the 2D separation. The separation in Panel (B) is obtained when the 2D separation is split into two segments, and different gradient elution programs are used in each segment. Finally, Panel (C) shows that the peaks can be further spread out by using isocratic conditions in the second dimension that are optimized over the course of the 2D analysis time to maximize use of the available separation space.
Reprinted with permission of Springer from Jandera, P., Ha´jek, T., Stankova´, M., 2015. Monolithic and coreeshell columns in comprehensive two-dimensional HPLC: a review. Anal. Bioanal. Chem. 407, 139-151. http://dx.doi.org/10.1007/s00216-014- 8147-3.
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