2 Concepts of 2D-LC
Multiple Heart-Cutting and High Resolution Sampling 2D-LC
2D-LC User Guide 24
Time-based mode in multiple heart-cutting
Figure 6 Time-based mode MHC
Time-based means that heart-cut times are defined in a timetable. This timetable
can be constructed according to the first dimension retention time of peaks in a
reference chromatogram. The time given in the sampling table corresponds to
the beginning of the cut parking in the reference chromatogram. The cut size is
fix and is given by t = V/F. The cut is parked by switching the valve at the time “cut
end”. Ultimately, only the cut end has relevance for the method and instrument
control. The cut end is displayed in preview as a reinforced line on the right side
of the bar. If you want to move the cut you can do it graphically by moving the bar
with help of the mouse or you can change the start time in the sampling table.
You can find more info in the chapter “Method Parameters” on page 125.
In MHC there is a limit of a few seconds on how close together you can place the
individual cuts. This limit is primarily dependent on the required switching time of
the 2D-LC valve. If you want to generate adjacent cuts you must use the High
Resolution mode, see “High Resolution Sampling - Peak Parking Principles” on
page 25. In multiple heart-cutting, loops should be overfilled (>100%). Please also
note the cut size time is related to the flow rate. If the
1
D flow rate is changed,
valve switch times are kept constant and the peak start time changes. Please
note that the reference signal from the loaded reference chromatogram
becomes invalid for a changed flow rate.
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