Metrohm 824 Easy Sample Changer - Manual (Page 39)

4.6 Method 4
824 Easy Sample Changer, Standard methods
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4.6 Method 4
Use:
For simple titrations (including KF titrations) or pH measurements (with-
out calibration). The initial addition of auxiliary reagents or solvents is
possible.
Required instruments:
• Metrohm titrator (Titrino or Titrando) or pH meter
• Metrohm Dosimat (optional)
• Metrohm 722/802 Rod Stirrer or 741 Magnetic Stirrer
• 2 external pumps (e.g. Metrohm 772 Pump Unit; Pump 1 for rins-
ing, Pump 2 for aspirating
Features:
After each determination the sample vessel is emptied by Pump 1 and
then the electrode is rinsed by Pump 2. The sample vessel is then emp-
tied again by Pump 1.
Preparation:
Fill a sufficiently large conditioning vessel with a suitable solvent and
place it in the highest rack position.
Procedure:
• (Start sequence) Initialize the sample changer
• Move to sample and lower lift to working position
• Switch on stirrer
• If a Dosimat is connected (optional): add auxiliary reagent or sol-
vent and wait until addition is completed
• Start titration/measurement and wait until it is completed
• Switch off stirrer
• Move lift to rinsing position and empty sample vessel
• Rinse electrode and empty sample vessel again
• Move lift to rotating position and allow electrode to drip
• (Final sequence) Move to conditioning beaker and immerse elec-
trode