Strength retention, definition

The concept of eluotropic strength has been invoked here without a rigorous definition. Snyder (130) developed a series of eluotropic values for solvents by using retention values measured on alumina columns. Colin and Guiochon (86) used a definition similar to that of Snyder to evaluate eluotropic strengths of methanol-water mixtures on various column surfaces. The eluotropic strength, e, was calculated by using the equation... 

Sometimes other variables must be investigated such as the pH and/or the ionic strength of the buffer in the mobile phase or the concentration of additives in the mobile phase such as for instance tensio-active substances in micellar chromatography. In such a case the first step in an optimization is to screen these factors and to identify the most important ones for the subsequent optimization. The screening (Section 6.4.2) leads to a definition of the experimental domain in which the optimum is probably situated. This is somewhat similar to the retention optimization step. It is followed by an optimization step (Sections 6.4 and 6.7), in which the most important variables are changed, often according to an experimental design. Similar methods are used in capillary zone electrophoresis. 

The apparent bulk that hair assumes after grooming is an important aesthetic characteristic often referred to as body, which can be considered a property associated with Robbins term style retention. Tolgyesi and co-workers (67) proposed the following definition of this hair assembly property Body is a measure of a hair mass s resistance to and recovery from externally induced deformation. This definition correlates well with the descriptive components springiness, volume, and stiffness that Wedderbum and Prall have obtained by applying statistical techniques to word association (58). The structural strength and resiliency of the hair mass are influenced by a number of independent parameters. Tolgyesi has identified the five most important parameters as fiber density... 

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