INFICON Explorer Portable Gas Chromatograph - Manual (Page 283)

Explorer Operator Manual
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Figure 20 Column A Compounds on the ECD
Figure 19 shows the six compounds analyzed on Column A. Two of these are
detected by the ECD, as shown in Figure 20.
The mid-range compounds are analyzed on Column B, with Column A acting as the
precolumn. The sample is injected onto Column A, and the heavy compounds are
prevented from entering Column B by adjusting the backflush time. The light and
mid-range compounds are allowed to pass from Column A to Column B. Before the
heavy compounds are able to pass into Column B, the flow is reversed, and the
heavy compounds are backflushed off Column A.
Some separation of mid-range compounds occurs on Column A, with the majority of
the separation occurring on Column B. Any light compounds present in the sample
are not separated and elute as an early peak, well separated from the Column B
compounds. The integration delay can be used to prevent this composite peak from
being included in the peak report.
The PID detects all of the 19 compounds analyzed on Column B, Figure 21 shows
12 of these. The ECD detects six of the 19 compounds, Figure 22 shows three of
these.