Multiple Heart-cutting

Typically, the gradient time in the second dimension is much longer for heart-cutting than with the comprehensive technique. The disadvantage of the standard heart-cutting techniques is that peaks cannot be sampled while a second dimension gradient is still running. In the examples shown here, the gradient from the second dimension is analyzing the first peak (purple), while the second and third peak (gray and yellow) elute from the first dimension column. The second dimension is ready when the 4th peak (green) elutes from the first dimension; this peak can be analyzed. As the second dimension is occupied again, the fifth peak (blue) cannot be analyzed.

This problem is addressed using a setup called multiple heart-cutting 2D-LC. Here, the sampling loops on the 2D-LC valve are exchanged with 6-position/14-port selection valves, which are equipped with six loops each. In this configuration, a peak can be cut out and stored, then analyzed as soon as the second dimension is free.

Peaks that are cut out and stored during a run are analyzed consecutively in the second dimension, even when the first dimension is still running. To avoid carry-over the peaks are analyzed in reverse order of storage in a single Multiple Heart-Cutting Valve.