Varian Micro-GC 490-GC, User Manual

Page: 49 / 83

Reference
Varian, Inc. User Manual Micro-GC Page 41
Figure 2:Separation principle of DMD
As illustrated in Figure 2, the DMD is equipped with two detectors, one for positive ions
and one for negative ions. Yet, the data produced by the DMD show a ‘normal’ two-
dimensional representation as the system will be ‘tuned in time’ to detect certain
species by setting compensation voltages to accommodate transmission of the
compound of interest in that particular part of the chromatogram. This ‘time-segmented’
detection thus leads to maximum selectivity for the application of interest as the matrix
is eliminated. The application specific method is saved inside the DMD hardware.
Micro-GC DMD Channel
The DMD channel is always located in the last position (against the backpanel)
The firmware recognises the DMD channel as a detector only, and automatically sets
the controls accordingly.
Position 2 DMD channel