Documenting water purity by electrolytic conductivity


EUROMET members are invited to a meeting to be held at DFM, with the purpose of discussing the formulation of collaborative projects in the field of electrolytic conductivity measurements. At the same time, the formulation of a proposal for the Fourth Framework programme should be discussed, either in reply to a dedicated call or as a Theme II proposal.

Aspects of projects could contaian (among other things):

A "market survey" to establish the need for traceable measurements. This does not stop at the present needs due to demands from e.g. FDA, but should also include wether present users of conductivity measurements would purchase certified reference solutions, and/or have their conductance meters calibrated, if such facilites where available. The survey should also map out the demand in the different ranges of conductivity.

The establisbment of a traceability chain starting from the secondary level; that is, from cells calibrated at NIST or with the use of NIST reference solutions.

The establishment of a primary standard of electrolytic conductivity and the neccessary comparisons with NIST to obtain mutual recognition of measurements.

Investigations into improvements/simplification of instrumentation for primary and secondary standards.

The development of new reference solutions, with better stability, ease of storage, immunity to e.g. atmospberic CO2, usability at high (80 °C) temperatures, etc.

Theoretical investigations into the transport properties of dilute electrolytic solutions.

Investigations into alternative calibration methods.

Final Report 1997-04-07

A meeting was held at DFM on September 19, 1995, with participation of the institutions listed above. The meeting served as a forum for exchange of information on the status and intentions of the institutions on measurement facilities for electrolytic conductivity.
Only NIST and OMH have already facilities providing well-established measurements of conductivity, while DFM, PTB and NMi are actively pursuing project to establish such facilities. DFM and PTB intends to build primary standards based on the NIST principle of a removeable center-section cell, while NMi will pursue a new design based on a cell divided in two by a movable piston/electrode and serving as one side in a ac-resistance bridge.
NIST, OMH and DFM are in progress with a Memorandum on Collaboration, which will contain an arrangement of comparisons leading to a Declaration of Equivalence on the measurement of conductivity for certain ranges and within stated limits.
As a result of the meeting, a proposal to the SM&T program was submitted on November 15, with DFM, PTB, NMi, NPL as well as three industrial companies as partners. The proposal was rated A2 and was not funded in the follow-up round.
Bi- and multi-lateral projects should therefore continue within the EUROMET framework.

Metrology in Chemistry (MC)
Hans D. Jensen, DFM (Denmark)
Coordinating Institute
DFM (Denmark)
Further Partners
NIST (United States of America)