Electrolytic conductivity at pure water level

Project Description

Electrolytic conductivity in aqueous solutions is one of the most used electrochemical measurement techniques in industry - it is relatively simple, cheap, and robust and is performing with a low measurement uncertainty compared with most other analytical techniques.
Since electrolytic conductivity is a sensitive measure of amount of ions dissolved in the solution a limit value for conductivity is a clear and simple quality specification for purity of water in general but also for high purity water. The relevant measuring range is below 1 mS/m (0.06 to 10 µS/cm at 25 °C). The European Pharmacopoeia as well as the Japanese and United States have indeed specified the demand for purified water, highly purified water and water for injection for the pharmaceutical industry based on conductivity. Sectors that also use conductivity limits for water purity are electical power production, food industry, electronic industry and analytical laboratories.

At these low levels it is not feasible to circulate water samples due to contamination. The main contamination is coming from carbon dioxide in ambient air. Therefore this comparison will be based on using a transfer standard calibrated at each laboratory in the appropriate conductivity and temperature range using closed flow systems. The transfer standard will be a commercial instrument with an appropriate cell for this conductivity levels.
The intercomparison is opened for both laboratories using primary and secondary calibration methods.

Final Report 2010-02-5

The project has been completed and the report can be downloaded here>>.

Metrology in Chemistry (MC)
Bertil Magnusson, RISE (Sweden)
Coordinating Institute
RISE (Sweden)
Participating Partners
DFM (Denmark)
PTB (Germany)