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Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the Measurement and interpretation of electrokinetic phenomena (IUPAC Technical Report)Abstract: In this report, the status quo and recent progress in electrokinetics are reviewed. Practical rules are recommended for performing electrokinetic measurements and interpreting their results in terms of well-defined quantities, the most familiar being the ζ-potential or electrokinetic potential. This potential is a property of charged interfaces, and it should be independent of the technique used for its determination. However, often the ζ-potential is not the only property electrokinetically characterizing the electrical state of the interfacial region; the excess conductivity of the stagnant layer is an additional parameter. The requirement to obtain the ζ-potential is that electrokinetic theories be correctly used and applied within their range of validity. Basic theories and their application ranges are discussed. A thorough description of the main electrokinetic methods is given; special attention is paid to their ranges of applicability as well as to the validity of the underlying theoretical models. Electrokinetic consistency tests are proposed in order to assess the validity of the ζ-potentials obtained. The recommendations given in the report apply mainly to smooth and homogeneous solid particles and plugs in aqueous systems; some attention is paid to nonaqueous media and less ideal surfaces.

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Theoretical considerations and experimental results are presented for the wicking process of a solid thin porous layer. This method was used for the solid surface free energy determinations. The commercial silica covered glass plates (Merck), used in thin-layer chromatography, were applied as a model material to check the derived equations as well as the experimental procedure. It is shown that the theoretical derivations, originating from Washburn's equation, and the obtained experimental results are consistent.The method should be especially useful for the solids of which a flat plate, suitable for contact angle measurements, cannot be obtained.