Moving Capillary Stream Switching
Any GC System that has been proposed for MDGC (2D GC), beginning with the first publication of Deans in 1968, is based on the same principal rules.
A first capillary column (pre-column) is coupled to a switching system, where the efluent of this column can either be switched to a detector, (monitor detector), or to a second capillary column (main column).
Small fractions of the first chromatogram can be accumulated on the second column, and separated under new chromatographical conditions, giving a lot more of information about the sample, than separated on a single column only. The single or multiple transfers into the second column are commonly named “cuts“ or “heart cuts“.
- MDGC principle
MCSS is a simple column switching system, where the column efluent is not directed by pressure variations.
The efluate itself is “delivered“ to the location where it is needed, just by moving the end of the pre column to that point.
This all takes place in a small hollow tip of glass, the “Glass dome“ located inside the GC.
The movement of the pre column is completely automized and controlled through the time functions of the GC
- MCSS Dom inside
The efluent of the pre column may be directed to the monitor detector or to the second column just by moving the end of it about 1 cm up or down.
The carrier gas fed into the dome (midle pressure inlet line) is split into a very small stream upwards, serving the second column, and a higher stream downwards to the monitor detector.
Along with this high stream the efluate of the pre- column is completely flushed to the monitor detector when no transfer is desired.
If the first column is pushed up for a few seconds, its efluate enters the second column and transfers the analytes eluted during that period of time.