Rapid density gradient centrifugation

Rapid Density Gradient Centrifugation of Polymer Latices... 

Figure 1. Density profile in the cell of the ultracentrifuge in case of standard and rapid density gradient centrifugation (rotor speed N = 40.000 min 1)...

The upper part of Figure 4 shows the results of the rapid density gradient centrifugation of a latex mixture of poly(styrene) and two chemically uniform co-... 

In Figure 5 the results obtained by rapid density gradient centrifugation of a polymer latex of unknown composition are shown. The gradient system consists of pure H2O and D2O. The density distribution of the particles has two broad peaks at the density values... 

In Figure 6 the result of a rapid density gradient centrifugation is shown using this system. It deals with a graft copolymer latex of butadiene and styrene acrylonitrile. The gradient media are different mixtures of 3-butene-2-ol and ethylene glycol. 

Figure 6. Density and extinction profile in rapid density gradient centrifugation of a graft copolymer latex of butadiene and styrene acrylonitrile (c 5 mg L 1, N — 40.000 min1, t 10 = 60 min, v = 546 nm)...

Thus the density and the density distribution and consequently the chemical composition and heterogeneity and also the cross-linking of polymer latex particles can be determined in a few minutes by rapid density gradient centrifugation. 

For the investigation of the chemical composition of dispersed particles, e. g. in polymer latices, a rapid method of density gradient centrifugation is developed. The method yields in a few minutes the density distribution and by this the distribution of the chemical composition of the particles. The standard density gradient centrifugation needs for the same results because of the time-consuming equilibrium gradient formation more than 15 hours. 

Cochet et al. [164] used GPC in studies on steroid-binding macromolecules. The method proved to be rapid and more efficient than the routinely employed density gradient centrifugation. Since only small-sample volumes are required, the method is suitable for microanalysis of pathological materials such as, e.g., excisions from human cancerous tissue. In patients with acute myelocystic leukaemia, as distinct from healthy persons, urine chromatography yielded an additional fraction that was eluted at a position of a lower This fraction was absent in 96% of persons without cancer and in the rest (4%) it occurred only in very low amounts by contrast, it occurred in 91% of cancer patients [165]. 

---