Exclusion limit lower

For all four sets of PEO standards the coefficient of determination (R ) for the linear calibration curves for the four linear columns in water and in water/methanol are better than 0.99, except for the PL PEO standards and the TSK GM-PWxl column in water/methanol. The coefficient of determination for the TSK GM-PWxl column in general is not as good as the other three linear columns. The coefficient of determination for the TSK PEO standards showed the least dependency on columns and mobile phases. The TSK GM-PWxl column has a lower exclusion limit in the high molecular weight range than TSK GM-PW, Shodex SB-806, and SB-806MHQ columns. 

Simple mineral oils [22] can be readily characterized. Figure 6.6 shows the separation of light mineral oils of the OM series on Styragel (500,200,100,60 A). The number in the description is an indication of viscosity. The peak of the envelope moves towards lower elution volume as the viscosity increases, with the one exception of OM15. This is thickened by including a polymeric additive, visible as a peak at the exclusion limit. 

At equilibrium conditions, at very low concentration, the elution volume of a macromolecule should be independent of the flow rate. However, with increasing molar mass in the UHMM range, in the absence of degradation, the elution volume strongly depends on the molar mass of the sample. This result does not depend on the concentration of the sample. This retardation effect occurs also at very low concentrations below the overlapping concentration c. The retardation of UHMM macromolecules has been studied by several workers it is a very complex effect and substantially stiU not well understood. The retardation effect is particularly meaningful in proximity to the exclusion limit of the columns and when the pore size approximately equals or is lower than the sizes of the macromolecules. A trivial conclusion is that for a successful fractionation of UHMM macromolecules without retardation effects, one must use SEC columns with ultralarge pore sizes. 

It has been found that, except high set relays, all other relays may not require the ALF to be more than 5. In such cases it is worth while to use two sets of protection CTs, one exclusively for high set relays, requiring a high accuracy limit factor (ALF), and the other, with a lower ALF, for the remaining relays. Otherwise choose a higher primary current than rated, if possible, and indirectly reduce the ALF as illustrated in Example 15.4 and meet the requirement with just one set of protection CTs. 

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