EFFECT OF SAMPLING RATE ON RESOLUTION IN COMPREHENSIVE 2-DIMENSIONAL LIQUID-CHROMATOGRAPHY

In ''comprehensive'' two-dimensional liquid chromatography, the column effluent from the first separation system (the first dimension) is se quentially sampled by the second dimension separation system. The tota l analysis time is largely determined by the speed of the second dimen sion separation system; the most retained component must elute before the least retained component of the next second dimension separation. Optimization of multidimensional separation systems requires that one understand the relationship between system resolution and the number o f second dimension samples across a first dimension peak. In this pape r, we study the theoretical and experimental aspects of this sampling process. To obtain high two-dimensional resolution, each peak in the f irst dimension should be sampled at least three times into the second dimension when the sampling is in-phase. If the sampling is maximally out of phase, there should be at least four samples per peak for high- fidelity separation. The sensitivity of the resolution with respect to the sampling phase is discussed in detail and shown to be insignifica nt when four or greater samples are taken across the first dimension p eak width. These results suggest optimal criteria for method developme nt with multidimensional chromatography.