2000 MS Hardware Maintenance
74
Chemical Ionization Options
Hints for Successful Operation of the MCI Module
1. Acquisition with each CI reagent using the MCI Module requires a unique
GC/MS method. The GC section method MUST contain
External Events
programming
(done in the Sample Delivery section) to select the CI reagent
in Channel A, B, or C. The MS method MUST have CI mode selected
with
the appropriate CI parameters designated.
2. It is always a good idea to close the chosen Channel of the MCI Module at the
end of a run so that the foreline pump is isolated from the CI reagent
. Otherwise,
the reagent will be pumped continuously from the Channel until it is
exhausted
.
3. The MCI Module may be used in several different ways to acquire data on a
sample for qualitative identification. Using deuterated reagents can provide extra
information when the data are compared with data from non-deuterated
reagents. Short reaction times will maximize the number of [M+D]
+
ions
compared to the number of [M+H]
+
ions.
4. With the relays off, unused reagent may be stored in a bulb attached to the MCI
Module for extended periods of time.
5. Fewer than three reagents may be connected to the MCI Module at any time.
However, the ports on the MCI Module must always be connected, either to the
restrictors and reagent vials/gas lines or plugged with the pin plugs supplied with
the module and accessory kit. The easiest way to keep all passages closed and
clean is to attach empty CI reagent bulbs in any Channels that are not currently
needed.
