Relevance to Differential IMS

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Hence of primary relevance to differential IMS at and around STP are the intermediate E/N where neither Equation 2.8 nor 2.11 applies. Various interpolations between the (E/N) 0 and (E/N) oo regimes were devised to cover the whole... 

E/N = 173 Td. Hence the hard-shell model for non-Blanc phenomena is misleading at E/N relevant to differential IMS. ... 

Often the most relevant characteristics of a separation method is peak capacity (pc)—the number of separable species for a particular sample. The pc is proportional to R, but also to the width of separation space—the range of separation parameters possible for a certain analyte type. As an illustration, an MS system with R = 1000 would produce pc 10 for a mixture of ions uniformly distributed between m/z = 500 and 1300 (a complex proteolytic digest) but only 10 for a mixture comprising m/z = 500-505 only (an isotopic envelope of a hypothetical compound). Hence broader separation space may compensate for lower R, which is typically the case for differential IMS in comparison with conventional IMS (Chapter 4). 

The first objective of this paper is to develop the differential importance measure in the context of dynamic systems including inter-component, functional dependencies, or more generally, systems described by Markov models. In such systems, the (un)availability of a component does not depend only on its characteristics but also on other system parameters, and its (im)availability in the system can be different from its (im)availabitity out of the system, see (Ou and Bechta-Dugan 2003). In this context, the partial derivatives with respect to the system parameters, or more generally, the directional derivatives (Do Van et al. 2008c), rather than to the components (un)availability, appears to be more relevant and is often preferred for design purposes. Hence, we develop the DIM based on the directional derivative... 

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