Agilent Technologies MSD 5977B Series Operating Manual page 158

6 Operating in CI Mode
To Use Other Reagent Gases
4 Click Isobutane (or Ammonia) Flow Adjust on the Execute menu.
There is no CI autotune for isobutane or ammonia in PCI.
If you wish to run NCI with isobutane or ammonia, load NCICH4.U or an existing
NCI tune file for the specific gas. For more information on CI operation using
ammonia, refer to Agilent Application Note
Reagent Gas for Chemical Ionization on the 5975 Series
Use of ammonia affects the maintenance requirements of the MSD. (See
C AU T I O N
Maintenance"
The pressure of the ammonia supply must be less than 5 psig. Higher
C AU T I O N
pressures can result in ammonia condensing from a gas to a liquid.
Always keep the ammonia tank in an upright position, below the level of the
flow module. Coil the ammonia supply tubing into several vertical loops by
wrapping the tubing around a can or bottle. This will help keep any liquid
ammonia out of the flow module.
Ammonia tends to break down vacuum pump fluids and seals. Ammonia CI
makes more frequent vacuum system maintenance necessary. Refer to the
Agilent 5977B Series MSD Troubleshooting and Maintenance Manual.
Frequently, a mixture of 5% ammonia and 95% helium or 5% ammonia and 95%
methane is used as a CI reagent gas. This is enough ammonia to achieve good
CI while minimizing its negative effects.
Carbon Dioxide CI
Carbon dioxide is often used as a reagent gas for CI. It has obvious advantages
of availability and safety.
158
on page 221 for more information.)
"Implementation of Ammonia
MSDs" (5989-5170EN).
5977B Series MSD Operating Manual
"CI