Electrophoretic mobility probe size

As mentioned above, experimental protocols are challenging in order to directly probe isolated polyelectrolyte chains, such as their sizes, counterion distributions, and electric potential variations inside and outside the coils. These quantities are sometimes deduced from measurements of other quantities, such as the electrophoretic mobility. The interpretation of data in these indirect measurements also depends heavily on reliable theories. The theoretical... 

Figure 3.7 Effect of matrix molecular weight on the electrophoretic mobility, using as probes restriction fragments of size (a) 72, (b) 603, and (c) 23 130 base pairs. Matrix polymers and their were hydroxypropylcellulose ( 100 kDa, 0 300 kDa), polyacrylamide (A 0.7-1.0 MDa, + 1.14 MDa), and hydroxyethylcellulose (O 1 32 MDa). Original measurements were by Barron, et al.(5,6).

The effect of field strength E on electrophoretic mobility was studied by Mitnik, et al. (26) and by Heller(27). Mitnik, et al. examined dsDNA fragments of size 72-23 000 bp passing through 1 MDa hydroxypropylcellulose solutions. For each probe, at lower fields p, is nearly independent of E. At larger fields, p, E for X (0.2,0.4) X increases as c is increased. At each matrix concentration, for each... 

In previous chapters, a range of experiments on aspects of polymer solution dynamics, from electrophoretic mobility to single-chain diffusion to linear viscoelasticity, has been treated(l). The previous chapter described results that were found with each method. What do these types of measurement tell us about how polymer molecules move through solution The answers to this question come in a substantial number of parts and pieces, best treated separately before being assembled into final conclusions. There are undoubtedly other parts and pieces that might have been discussed, such as the consequences of changing the relative size of matrix and probe polymers, or the consequences of polymer topology. This chapter stays with answers most central to our purpose. 

---