4. Conclusion

In addition to filtration, membranes have other analytical applications. They can be used in dialysis, reverse osmosis, purification, enrichment, controlled addition of reagents, or in sampling and coupling systems between process and analytical systems. Flow-force fractionation, or polarization chromatography, can illustrate the development of new methods. It is a means of measuring the size of colloidal particles in a system, similar to those used in tangential filtration since it involves suspension flow close to a porous wall. The technique involves passing the solution through a capillary channel, one wall of which is made of a membrane, and determining, for a given filtrate flow rate through the membrane, the passage time of the various particles, thus obtaining the equivalent of a size exclusion chromatogram.

Filtration techniques are used in a wide range...