Figure 3.

Illustration of the function of Active Solvent Modulation (ASM) for coupling the two dimensions of separation in a 2D-LC system. This valve has eight ports and four positions. Postions A and C are functionally identical to those of a conventional 8- or 10-port two position valve (e.g., see Figure 2). In positions B and D, however, part of the flow from the ²D pump is split and travels through the bypass capillary. This portion of the flow joins the stream of fluid exiting the sample loop before the mixture leaves the valve and enters the ²D column. In this way, this split part of the ²D flow acts as a diluent for the ¹D effluent fraction injected into the ²D column.