2D-LC flow path
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2D-LC flow path

2D-LC Flow path diagram with transfer times
Figure 2D-LC Flow path diagram with transfer times

A 2D-LC system may contain multiple detectors in each dimension. In the first dimension, it is also possible to have no detector at all.

As an example, the figure above shows a system with two detectors in each dimension. The eluent is separated by the first-dimension column COL1, arrives at the first detector DET1,1 in the first dimension, and some time later at the second 1D detector DET1,2. The eluent is carried further to the 2D-LC valve, where cuts are parked. The 2D-LC valve (and optionally connected multiple heart-cutting valves) operate as an injector for the second dimension. By switching the 2D-LC valve, a cut is injected to the second-dimension flow path. This is when the ²D run starts; it defines the zero for the second dimension retention time. The flow from the second dimension pump PMP2 carries that cut to the second dimension column COL2, where it may be further separated. The flow continues to the detectors. It first arrives at the first ²D detector DET2,1, and a bit later at the second ²D detector DET2,2.

The figure above (2D-LC Flow path diagram with transfer times) includes transfer times t measured between each detector and the 2D-LC valve:

Table: Transfer times

Transfer time

Flow path

t1,1

Between first ¹D detector and 2D-LC valve

t1,2

Between second ¹D detector and 2D-LC valve

t2,1

Between 2D-LC valve and first ²D detector

t2,2

Between 2D-LC valve and second ²D detector

These times t correspond to transfer volumes V, which can be converted by multiplication with the applicable flow rates F:

V = F · t

You set these transfer volumes in the 2D-LC configuration. They are used for calculating the transfer time and switching the valve after a signal was seen by the detector. The transfer volume for the transfer time t1,2 in the first dimension is by default calculated as half the volume of the detector flow cell plus the volume between the detector flow cell and the 2D-LC valve.

When checking the system suitability values for a ²D column: Use the transfer time as the void time that you enter in the column parameters (see Check the column performance).

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