Dealing with Wandering First-Dimension Peaks in 2D-LC Separations: The retention of large molecules, such as peptides and proteins, is strongly dependent on mobile-phase composition and temperature. Consequently, the retention times ([t.sub.R]) of these molecules often fluctuate from one separation to the next. In two-dimensional liquid chromatography (2D-LC), this fluctuation can be challenging to deal with, especially if only one or a few specific peaks in the first dimension ([.sup.1]D) separation are targeted for further separation. In this installment, we describe instrumental concepts that are useful for coping with this challenge

In October of 2019, I invited Dr. Patrik Petersson to contribute an 'LC Troubleshooting' article describing some tips and tricks for minimizing fluctuating first dimension ([.sup.1]D) retention times in two-dimensional [...]