17
Vessel Cleaning and Inspection
Vessel Cleaning and Inspection
WARNING
Proper precautions must be taken to avoid contact with reagents or reagent vapors. Protective gear should
be worn as outlined in the user’s safety program for hazardous materials and the reagent manufacturer’s
safety data sheet. Refer to these guidelines for proper handling and disposal of the reagents.
Liners and Plugs
1.
Rinse the liners and plugs with deionized water and allow to dry completely before use.
2.
Inspect liners and plugs. Liners should be smooth and white.
• Liners that are rough in texture on the outside may be ok to run but will need to be grouped with like
vessels.
• Liners that have stretching along top with a visible dark line must be discarded. See "Vessel Assembly" for
preventative measures.
3. If measuring ppm, ppb and/or ppt analyte levels, proceed with steps below.
4.
Clean liners and plugs with hot, soapy water and foam brush. Rinse thoroughly with deionized water and allow
to dry completely before use.
NOTE
Micro-90® cleaning solution works well on Teflon. Avoid detergents that contain ingredients that could
cause potential contamination such as Na and P. Avoid abrasive cleansers and stiff brushes which can
scratch the Teflon surface.
5.
Clean liners and plugs using the microwave as outlined below. All vessel components must be dry before use.
5.1.
Add 10 mL of acid that had been used for sample digestion, HNO
3
, HCl, H
2
SO
4
, H
3
PO
4
or HF.
5.2.
Prepare vessel and turntable as outlined in manual.
5.3.
Depending on acid type, select and run the appropriate method in the One Touch directory.
• HNO
3
, HCl or HF: Select “Easy Prep Clean.”
• H
2
SO
4
or H
3
PO
4
: Select “High Temp Clean”. If “High Temp Clean” is not available, create a One Touch
method with the following parameters: Temperature=240 °C, Sample Type=Organic, Hold Time=15
minutes and TempGuard=270 °C.
5.4.
Wait for vessels to cool below 80 °C before opening microwave door.
5.5.
Discard acid and rinse the liners and plugs with deionized water.
Liner and plug Bake-out Procedure
As needed: The bake out procedure can be used to remove residual acid vapors and other trapped gases from the
Teflon® material. Trapped gases can potentially cause uneven heating between new and used liners.
The bake out procedure can be used to remove residual NOx gases from liners following digestion with HNO
3
that
may interfere in subsequent runs. This procedure has been successfully used to remove sulfur contamination from
the Teflon following digestion of samples with high sulfur content.