Applications of SEC

SEC allows, with respect to the basic separation mechanism, separation of particles according to differences in their effective sizes. Its application to the separation of particles in the submicron size range is limited only by the availability of column packing materials having sufficiently large pore size diameters. In order to cover as large a range of sizes of commonly fractionated particles as possible, the column packing material should have the pore size distribution from a few tenths of nanometres to hundreds of nanometres. For technical reasons, it is only possible to prepare the packings with a limited range of pore sizes and the SEC separation system is composed of an assembly of several columns in series, packed with several particle packing materials of different porosities, or another possibility is to use only one column packed with a mixture of several different packing materials with various porosities. The selectivity and the resolution of such a separation system is, however, lower than a system with a more homogeneous distribution of the pore dimensions.

Besides standard particle size separations, SEC has been successfully applied to the analytical characterization of micelles and submicron particles. Under the appropriate experimental conditions it can be used for separations in organic solvents as well as in water, at elevated temperatures, etc. An interesting application of SEC is so-called inverse SEC. The difference, as compared to conventional SEC, lies in the column packing particles being analysed from the viewpoint of the pore size distribution or average pore size dimensions, using a series of well-characterized size standards.

The analytical application of SEC for the determination of PSD is related to the use of either any calibration procedure and/or to the coupling of the separation system with the detector, the response of which is proportional to the size-related property of the analysed particles such as, e.g., the intensity of the scattered light. The coupling of the concentration-sensitive detector and a size-sensitive detector, together with the use of an appropriate calibration procedure for the separation system, allows extraction of more information on PSD and other structural parameters of the particles under study.

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Solar Panel Basics

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