How to clean the metal lens plate and special assemblies on a Waters instrument - WKB64202

OBJECTIVE or GOAL

Clean the metal lens plate and special assemblies on a Waters instrument.

ENVIRONMENT

• AutoSpec Premier
• GCT
• GCT Premier
• Quattro Micro GC

PROCEDURE

1. Make a slurry of aluminum oxide (alumina) and the minimum amount of methanol necessary. Some methods use jeweler's paste in place of the alumina/methanol, with excellent results.
2. Using cotton swabs with a wooden shaft (cut down to a 2-inch total length) and a suitable support sleeve (as appropriate). Place the swab into a small Dremel tool (in place of the typical drill bit) so that the swab is firmly held.
3. Place some aluminum oxide (alumina) slurry or jeweler's paste onto the cotton swab tip and start the Dremel spinning.
4. Gently apply the spinning swab tip to the metal optic surface until it is clean.
   • With EI/CI inner source ion chambers, do not push the tip into the filament electron entrance hole; this would cause irreversible damage.
5. Wash clean the metal optic with copious amounts of distilled/Milli-Q water, while wiping it constantly with clean swabs.
6. Dry the metal part using lint-free tissue.
7. If possible, suspend the metal parts in a clean, appropriately sized beaker using paper clips.
8. Solvent-wash (using the highest grade possible) the metal parts in a suitable sonicator for 5 to 10 minutes, using the following sequence.
   • Hexane
   • Toluene
   • DCM
   • Acetone
   • Methanol
   • Milli-Q water
9. Before reassembly, dry the parts using lint-free tissue.

ADDITIONAL INFORMATION

• The listed procedure carries health risks, and the appropriate precautions must be taken.
• There are several ways to clean Waters GCMS optical metal parts. The method outlined above uses the most commonly available materials and tools. Some engineers prefer to manually clean the metal optics with cotton swabs, without using the Dremel.
• Throughout the procedure, wear gloves that have been washed with copious amounts of pure, distilled water, to remove any possible PEG contamination.
• Not all blemishes on metal spacers, lens plates, or ion chambers/special assemblies can be removed; heat and the ion beam can cause irreversible discoloration.
• Higher Dremel speeds provide easier and faster cleaning, but they also tend to break the swab shafts more frequently.
• Solvents have a number of stabilizers added to them to prevent degradation. The solvent sequence given here steadily reduces the extraneous contamination to ppb levels.