THE present chapter discusses several strategies and considerations for the prac-tical application of the analysis principles outlined above. Throughout, we assume that a successful sedimentation experiment was carried out, as described in Part I [1], showing convection-free sedimentation at an adequate rotor speed, observed over a sufficient period of time with a suitable selection of optical detection. Further, we assume that the non-interacting species and distribution model is really applicable, either because the system under study is practically non-interacting (which can usually be verified through experiments in a concentration series), or because the non-interacting system model is used as an approximation, for example, for an effective sedimenting particle of an interacting system [70, 75, 76], or as a vehicle for the determination of a signal weighted-average sedimentation coefficient. Sedimentation processes of systems with attractive or repulsive interactions will be the topic of a forthcoming volume, but many of the principles discussed here will also apply. The following will focus on strategies that address the key problem of SV of non-interacting systems, which is to distinguish the extent of diffusional boundary spread from the differential migration arising from different size particles.

8.1 GENERAL FITTING STRATEGIES 8.1.1 Data Preprocessing Ordinarily there should be no data preprocessing required, because all analysis parameters relating to sedimentation and optical signal are explicitly part of the fitting model. However, before a fitting session can start, the following operations may have to be carried out: