multi EA 5000
Sulfur analysis with the Coulometric Sulfur Module
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10.3 Operation
10.3.1 Preparing the measuring cell
Preparing the measuring cell includes the following steps:
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Preparing the electrolyte solution
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Performing the end point routine
Two further solutions are required for the end point routine and for the check of the
measuring cell. The creation of these solutions is also described in the following.
Preparation of the electrolyte
solution
WARNING
Risk of chemical burns
100 % acetic acid (glacial acetic acid) can cause severe chemical burns. Gases may de-
velop during shaking.
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Wear protective clothing when preparing the electrolyte solution. Work under an ex-
tractor.
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Observe all instructions and specifications in the safety data sheet.
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Prepare the electrolyte solution one day before its use.
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Reagents required: 10 ml acetic acid 100 % (glacial acetic acid), 10 g sodium ac-
etate, 5 g potassium iodide, 7.5 g potassium chloride
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Dissolve the given amounts of sodium acetate, potassium iodide and potassium chlo-
ride in a 1-liter volumetric flask. Wait until the salts have completely dissolved.
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Carefully add 10 ml of glacial acetic acid. Keep moving the flask while pouring the
acid. Carefully shake the solution.
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Fill the volumetric flask with ultrapure water up to the mark. Carefully shake the so-
lution.
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Fill the measuring cell with approx. 100 ml of electrolyte solution (to the level of the
port for manual metering).
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The electrolyte solution has been prepared and added to the measuring cell.
Performing the end point rou-
tine
A sodium sulfite solution (1000 mg/l) is required for the end point routine:
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Reagents required: 393.9 mg sodium sulfite
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Fill a 100 ml volumetric flask with the specified quantity of sodium sulfite.
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Fill the volumetric flask with ultrapure water up to the calibration mark. Shake the
flask until the sodium sulfite has completely dissolved.
Storage and handling of the sodium sulfite solution:
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The solution is sensitive to atmospheric oxygen and may thus be stored in a refriger-
ator for no longer than 1 month.
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For the end point routine, only 2 – 10 μl of the master solution are required.
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For better metering, diluted solutions can be used.
For the end point routine, the cell potential is set to the optimum operating range of the
measuring cell.
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Operating range: 110 to 160 mV
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Optimal operation range: 120 mV
