Endress+Hauser Analytik Jena multi EA 4000, Руководство по эксплуатации

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Operation multi EA 4000
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6.4.2 Preparing the electrolyte solution
WARNING
The 99% acetic acid and nitric acid and thymol used to prepare the electrolyte solution
can cause severe chemical burns!
Wear the appropriate protective clothing when preparing the electrolyte solution! Ob-
serve all specifications in the safety data sheets!
Reagents required:

200 ml acetic acid c = 99 %

1.0 g thymol

4 ml nitric acid conc.

0.3 g thymol blue

4 g gelatin

500 ml methanol
Prepare the electrolyte solution as follows:
1.
Solution A:
Fill 500 ml ultrapure water into a 1000 ml volumetric flask, add 4 ml HNO
3
(conc.), carefully add 200 ml acidic acid and fill with ultrapure water up to the
marking.
2. Solution B1:
Mix 4 g gelatin in a beaker with 400 ml ultrapure water, allow to swell for 3 hours
and then dissolve whilst heating to 35–45 °C.
3. Solution B2:
Dissolve 1.0 g thymol and 0.3 g thymol blue in a beaker in 500 ml methanol.
4. Solution B:
After cooling solution B1 to (18–22) °C add it slowly to solution B2 whilst stirring,
filter, transfer into a 1000 ml volumetric flask and fill with ultrapure water up to
the marking.
5. Solution C – finished electrolyte:
Pipette 8 ml of solution B in a 100 ml measuring cylinder and fill with solution A to
100 ml, or
pipette 40 ml of solution B in a 500 ml measuring cylinder and fill with solution A
to 500 ml.

When stored at 4 ± 3 °C in well-sealed bottles, solutions A and B can be kept for ap-
prox. 6 months.

The finished electrolyte solution (solution C) can be kept for approx. 30 days if kept
in a well-sealed glass container at 20–25 °C.
Storage and durability of
the electrolyte solutions