2000 MS Hardware Maintenance
52
Chemical Ionization Options
Adding Liquid CI Reagents to the MCI Module
The addition of liquid reagents to the MCI Module is accomplished in much the
same manner as addition of liquid reagent to the single Liquid CI option (LCI).
The LCI liquid filling process is shown in detail on the Saturn Maintenance
Tutorial CD under the heading
MS Maintenance … CI Installation
.
In the MCI Module, this sequence is followed:
1. Turn off all relays related to the MCI module.
2. If you have a
turbo pump system
, skip this step. If you have a
diffusion pump
system:
For each channel that will be worked on, close the associated needle
valve by turning the knob clockwise. This will reduce the inrush of air into the
vacuum system when channels are reactivated.
3. Remove the MCI cover by loosening the thumbscrew on the front cover.
4. Loosen (but do not remove) the four screws located between the solenoid valves
on top of the MCI Manifold. Any of the liquid CI reservoirs may now be removed
by rotating the bulb and pulling down, away from the manifold. Be careful not to
break the fragile necks of the bulbs. Be sure to keep bulbs installed in all
positions of the MCI Manifold, whether they contain a liquid reagent or are empty.
Hazardous chemicals may be present. Avoid contact, especially when
replenishing reservoirs. Use proper eye and skin protection.
5. Use the 5 mL syringe supplied in the Accessory Kit to fill the bulb halfway with 3
mL of the chosen CI reagent liquid.
6. Carefully reinsert the bulb in the ¼ inch inlet port of the channel.
7. Retighten the screws on top of the module. The bulbs will be held firmly by the O-
ring seals after the screws are tight.
8. Replace the MCI cover and tighten the thumbscrew to hold it in place.
9. After installing CI reagent liquids, and each time a reagent liquid or gas is
installed, always use care when first opening the CI valves.
10. If you have a
turbo pump system
, skip this step. If you have a
diffusion pump
system
, first turn on the relays, then open the needle valves slowly by turning
the knobs fully counterclockwise, to clear out the air in the reservoir bulbs. After a
few seconds, monitor the foreline pressure. Do not allow the pressure to exceed
500 mTorr for more than twenty seconds or the diffusion pump will shut down.
Return the valve settings to ½ open or their previous setting (approximately 7
turns).
11. Do not turn on the filament or multiplier for 2-3 minutes after opening the CI
valves. A convenient way to verify that air and water have been removed
sufficiently is to check the ion gauge pressure with the CI valves open. Verify that
the pressure has returned to less than 35 x 10
-6
Torr before turning on the
filament and multiplier.
Adding Gaseous Reagents to the MCI Module
To change a channel from liquid operation mode to gaseous, follow the
procedure given in the MCI Module Maintenance section.
