Perkin-Elmer TITAN MPS, User Manual

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103
Cleaning
Complete Digestion
After a complete digestion it is sufficient to clean it several times with
demineralised water. (e. g. 3x 20 ml)
Nevertheless it is advisable to perform a blank digestion prior to a new series of
digestions. (such as for example if the purity grade changes from % to ppm, ppb,
sub ppb).
Partial Digestion
If an incomplete digestion occurs, mechanical removal of the undigested
compounds with clean wipes, a sponge or brush may be used though a cleaning
digestion method using a suitable acid mixture is recommended. The chemistry of
the samples used and the reason for the incomplete digestion will dictate the
appropriate cleaning procedure.
How to Perform a Blank Digestion
To carry out a blind digestion it is advisable to create a new program with only a
three to five minute heating-up time and 10-15 minute holding time for the final
temperature.
The final temperature depends on the final temperature of the subsequent digestion
and on potential gas development.
If no gas development is anticipated when carrying out the blank test the final
temperature can be selected analogous to the next digestion temperature.
If gas development is to be expected, the final temperature must be raised by 10 °C.
DPC Cap Maintenance
From time to time the glass ring, prism and polarization foil installed in the TFM
cap for pressure control will need cleaning. This is necessary if the pressure results
of digestions begin to vary significantly from historical results. This will also be
checked during periodic preventative maintenance visits.