Population density distribution resolution

In part I, Timm and Rachow Q) describe an algorithm for interpretation of chromatograms for imperfect resolution. The instrument was one of low plate counts, and yet population density di.,. ributions consistent with theoretical, kinetic models were achieved (, ) Research, using high plate count columns, shows that convergent distributions are achieved and that results are not a function of instrument resolution. Linear polystyrene resins had a polydispersity in the interval 1.5 M /M 2.0. 

A22. Anderson, D. W., Nichols, A. V., Pan, S. S., and Lindgren, F. T., High density lipoprotein distribution. Resolution and determination of three major components in a normal population sample. Atherosclerosis 29, 161-179 (1978). 

Particle-size and mass distribution curves, along with information on particle porosity, density, shape, and aggregation, can be obtained for submicrometer- and supramicrometer-size silica materials suspended in either aqueous or nonaqueous media by field-flow fractionation (FFF). Narrow fractions can readily be collected for confirmation or further characterization by microscopy and other means. Among the silicas examined were different types of colloidal microspheres, fumed silica, and various chromatographic supports. Size distribution curves for aqueous silica suspensions were obtained by both sedimentation FFF and flow FFF and for nonaqueous suspensions by thermal FFF. Populations of aggregates and oversized particles were isolated and identified in some samples. The capability of FFF to achieve the high-resolution fractionation of silica is confirmed by the collection of fractions and their examination by electron microscopy. 

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