horiba 5002S-10C, Инструкция по эксплуатации

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Reference

Standard solutions
 Selecting standard solutions

Perform calibration using standard solutions of 100 mg/L and 1000 mg/L.
Approximate concentrations can be measured.

For more accurate measurements, prepare standard solutions which
have the following concentration relationship for calibration.
Standard solution with low concentration < Sample solution <
Standard solution with high concentration
In this case, prepare two standard solutions so that the concentration of
one of the two standard solutions is approximately 1/10 of that of the
other standard solution.
 Temperatures of the standard solution and sample
solution
When taking measurements, match the temperature of the standard
solution in calibration and the temperature of the sample solution in
measurement.
This reduces the errors in the ion concentration measurement due to the
electromotive force changes caused by the temperature changes of the
glass electrode for pH measurement.
Measurement errors become larger as the difference between the
temperatures of the standard solution and sample solution becomes larger.
 Handling of standard solutions after use
Do not return a standard solution to its original container after it has been
used once.
The composition and concentration of the standard solution will have
changed, which will cause measurement errors because accurate
calibration will not be possible.
 Storing standard solutions
Put the standard solution in a container that can be hermetically sealed,
seal the container hermetically, and store it in a cool and dark place. If
standard solution is stored in a state in which it is open to the atmosphere,
the concentration will change due to, for example, evaporation and the
mixing of impurities.