A PFG-NMR Study of Restricted Diffusion in Heterogeneous Polymer Particles.
The diffusion resistance to monomers during heterogeneous polymerization of polyolefin particles may have a significant effect on the observed activity. This diffusivity is, in general, unknown. To gain more information on this diffusion resistance in such systems, PFG-NMR has been used to measure the diffusion of organic solvents in various systems of porous polymer particles. In such systems the complex morphology and geometry demands careful analysis of the PFG-NMR attenuation curve. In this study, effects from restricted diffusion, domains having different diffusivity, and internal magnetic field gradients are expected. Thus, the obtained diffusivities have to be considered carefully, and a way to analyze the data taking these effects into account is presented. Copyright 2001 Academic Press.
More than 260 pork samples of domestic and foreign origin were analysed for the study of typification and genetic traceability of this kind of meat. The correspondence between raw material obtained after slaughtering, refrigerated or frozen meat and cooked product was evaluated, using a suitable set of primers, by means of PCR-RAPD (Random Amplification of Polymorphic DNA). Using tne same technique, samples were analysed in order to distinguish between meats from domestic or foreign pigs. The results, although not definitive, often allowed the origin of the raw material to be ascertained even for products such as cooked ham. For repeatability problems inherent in the method, a simultaneous analysis of unknown and reference samples is required.