General Maintenance 6ď€
5977B Series MSD Operating Manual 147
Chemical residue
Only a small portion of your sample is ionized by the ion source. The majority
of any sample passes through the ion source without being ionized. It is
pumped away by the vacuum system. As a result, the exhaust from the foreline
pump will contain traces of the carrier gas and your samples. Exhaust from
the standard foreline pump also contains tiny droplets of foreline pump oil.
An oil trap is supplied with the standard foreline pump. This trap stops only
pump oil droplets. It does not trap any other chemicals. If you are using toxic
solvents or analyzing toxic chemicals, do not use this oil trap. For all foreline
pumps, install a hose to take the exhaust from the foreline pump outdoors or
into a fume hood vented to the outdoors. For the standard foreline pump, this
requires removing the oil trap. Be sure to comply with your local air quality
regulations.
The fluids in the diffusion pump and standard foreline pump also collect
traces of the samples being analyzed. All used pump fluid should be
considered hazardous and handled accordingly. Dispose of used fluid
correctly, as specified by your local regulations.
Ion source cleaning
The main effect of operating the MS in CI mode is the need for more frequent
ion source cleaning. In CI operation, the ion source chamber is subject to more
rapid contamination than in EI operation because of the higher source
pressures required for CI.
The oil trap supplied with the standard foreline pump stops only foreline pump oil. It
does not trap or filter out toxic chemicals. If you are using toxic solvents or
analyzing toxic chemicals, remove the oil trap. Do not use the trap if you have a CI
MSD. Install a hose to take the foreline pump exhaust outside or to a fume hood.
When replacing pump fluid, use appropriate chemical-resistant gloves and safety
glasses. Avoid all contact with the fluid.
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