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1. | Heat reagent water in a glass beaker while adding Bis and stirring. |
2. | When precipitation is observed (saturation), add HCl until pH = 7 as tested with pH paper. |
3. | Cool solution (a gel forms in the beaker), then decant the water and place in a warm oven until dry. |
4. | Scrape dry remains from the bottom of the beaker and place in a vacuum desiccator to cool. |
5. | Take first weight quickly upon removal from desiccator when making up the buffer. See ODP Tech Note 15 for complete instructions on making up the powdered buffer. |
6. | Redry in oven and cool in desiccator each time prior to weighing. |
7. | Make new Bis buffer at the beginning of each expedition. |
Main instrument panel
Figure 1. Main instrument panel.
Instrument calibration
To ensure accuracy of sample measurements, the titrator settings must be optimized. Calibration of the system includes calibrating the electrode, selecting a dispensing rate program and calculating a standard ratio.
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- Set your Stability Criteria for each step of the program: Measurement continues until Stability Criteria (mV/s) is satisfied.
- Select your Increment for each mV level (initial to 150, 150 to 220 and 220 to 240): How much acid is added in each increment.
- Set the Time Out for each step of the program: Seconds until rate program times out if Stability Criteria is not satisfied.
- Save To File.
Figure 3. Selecting a titration rate. A new dispensing rate program can also be created.
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