A QUANTITATIVE APPROACH TO THE ANALYSIS OF SUPERMICRON DISPERSIONS BYFIELD-FLOW FRACTIONATION WITH UV-VIS DETECTORS - THE APPLICATION OF AN ABSOLUTE METHOD

Quantitative analysis in field-flow fractionation is becoming a necess ary requirement for routine applications, instrumental optimization an d scale-up to preparative separations. The use of detection systems wh ich show complex dependence on sample characteristics (i.e. UV spectro metry) has hindered the application of quantitative methods of analysi s in field-flow fractionation. A standardless model, shown valid in fl ow-through, homogeneous systems, is applied here to a heterogeneous sy stem (dispersed supermicron particles) in field-flow fractionation by single peak area measurements. Absolute analysis in the fractionation of spherical silica particles for high-performance liquid chromatograp hy column packing by gravitational field-flow fractionation with UV-Vi s detectors is presented. It has been shown that for such samples exti nction coefficients are independent of sample concentration and are de termined by the size and density of the particles. The accuracy of suc h an approach to absolute analysis is discussed.