Enter a number in the text box to indicate the amount of "non-mixing volume" (in uL) present before the column inlet.
Usually, the majority of the non-mixing volume comes from tubing and connectors between the pump and the column inlet, and from the pump itself. Non-mixing volume is depicted in the diagram below:
Non-mixing volume does not disperse the gradient like mixing volume does. Instead, it just makes it take longer for the programmed gradient to reach the column inlet.
The graph below shows an ideal gradient profile going from 0% B to 100% B in 5 min without any non-mixing volume.
The graph below shows the same gradient profile, delayed by a large non-mixing volume.