Dispersion sensing-zone techniques

Sensing-zone techniques have been applied to oil-in-water emulsions, although they cannot distinguish between dispersed droplets and solid particles [66], Unless an emulsion sample contains no particles, or is very well characterized, the results... 

A particle or droplet-sizing technique in which the flow of dispersed species in a capillary, between charged electrodes, causes changes in conductivity that are interpreted in terms of the sizes of the species. Coulter is the brand name for the automated counter. See also Sensing Zone Technique. 

Care must be taken in selecting an indirect method since these require assumptions about either the real size distribution, the shape, or the process on which the analysis is based. For example, conductometric sensing zone equipment relies on the assumption of sphericity, which is usually reasonable for emulsion droplets, but often is not reasonable for particles in a suspension. Similarly, light-scattering techniques are reliable only if the particle shape and refractive index are known or assumed, and adsorption analyses rely on model adsorption isotherms, the uniformity of particle size and porosity, and the orientation of adsorbed species. Each technique has its own limitations. For example, concentrated dispersions... 

This technique differs from flow injection analysis in the sense that whereas in the latter technique the sample plug is injected into a flowing stream of reagent, in the former technique plugs of reagent are injected into a continuous stream of the sample. Under these conditions the amount of sample in the zone of the reagent will increase as the dispersion increases. The sample will become well... 

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