8 Maintaining the MMI
To Clean the Multimode Inlet
Maintaining Your GC 139
To Clean the Multimode Inlet
This procedure explains how to clean the Multi Mode Inlet (MMI). Depending on the inlet mode
used, the liner installed, and the cleanliness of the sample, the frequency of cleaning may
range from weekly to monthly. Start with a visual inspection of the inlet bottom whenever
changing the liner. A small ring of material will collect at the bottom of the inlet when injecting
dirty samples such as food extracts or solid waste. Try an initial cleaning schedule of every two
weeks for dirty samples and every two months for clean samples and adjust as needed.
1 Gather the following:
• Cleaning kit, multimode inlet (G3510-60820). Contains 5 each abrasive swabs and
5 each cotton swabs.
• Solvent for cleaning (at least 25 mL of acetone, isopropanol, or hexane, whichever is
most appropriate for your sample matrix).
• 100 mL beaker or similar container to the catch solvent rinse.
2 Manually set the inlet and oven temperature to < 40 °C, and wait for the inlet, oven, and
other parts you might come into contact with inside the oven, to cool before continuing.
Alternately, place the GC in maintenance mode: Maintenance > Instrument > Perform
Maintenance > Maintenance Mode > Start Maintenance.
Be careful! The oven and/or inlet may be hot enough to cause burns. If the inlet is hot, wear
heat-resistant gloves to protect your hands.
3 Turn off the GC.
Wear clean, lint-free gloves to prevent contamination of parts with dirt and skin oils.
4 Remove the inlet liner. See “To Change the Liner and O-Ring on the MMI” on page 134.
5 Remove the column from the inlet. See “To Install a Capillary Column with the Multimode
Inlet” on page 126.
6 Place the glass beaker or other container in the GC oven, below the MMI inlet, so it will
catch any solvent that drips through the inlet body.
7 Moisten a cotton swab with solvent and wipe the inside bottom seal of the inlet repeatedly
to remove any loose material from the MMI. If desired, the cotton swab can be used to
clean the bore of the inlet. For most samples, this is not necessary. Dispose of the swab
after a single use.
8 Using a dry abrasive swab, place the swab all the way to the bottom of the inlet and with
moderate pressure, twist the swab forwards and backwards while it is in contact with the
bottom of the MMI (approximately 20 cycles should be sufficient). The abrasive swab can
be used multiple times.
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