72 Operation Manual
4 Operating in Chemical Ionization (CI) Mode
Setting Up Your MS to Operate in CI Mode
Setting Up Your MS to Operate in CI Mode
Setting up your MS for operation in CI mode requires special
care to avoid contamination and air leaks.
• Always use the highest purity methane (and other reagent
gases, if applicable). Methane must be at least 99.9995% pure.
• Always verify the MS is performing well in EI mode before
switching to CI.
• Make sure the CI ion source is installed.
• Make sure the reagent gas plumbing has no air leaks. This is
determined in PCI mode, checking for m/z 32 after the
methane pretune.
• Make sure the reagent gas inlet line is equipped with gas
purifiers (not applicable for ammonia).