NMR Aquametry

摘要

Hydrogen Nuclear Magnetic Resonance (1{sup left}H NMR) is a direct method to determine the hydrogen content and with it the water content (moisture) in solids. Simultaneous it is highly sensitive probe of local, molecular-scale dynamical information, allowing characterizing structure molecular dynamics in hydrogenous liquids as well as in hydrogenous solids. Moreover, Magnetic Resonance Imaging (MRI) - well known as a tool in medical diagnosis - provides insight into the spatial distribution of hydrogen content and molecular mobility. Therefore, it stands to reason, that 1{sup left}H NMR is highly demanded in investigating the mechanisms of water-solid interaction, as dissolution, chemical reaction and sorption. A variety of scientific disciplines benefit from these findings. NMR is a well established method for fast and accurate moisture determination in pharmaceuticals, cosmetics and foodstuffs. In pharmacological research, the on-line monitoring of the disintegration process of starch tablets in water can help to develop drugs with controlled availability of the active substances. Manifold applications are reported from polymer researchers. In development of highly water-proof fiber-reinforced plastics (e. g. for windmill blades, hulls, airplane components) or corrosion protective rubber linings, it is important to study the water-uptake of these materials as well as their swelling and plasticizing due to water ingress. Many durability problems of building materials such as frost attack, embedded steel corrosion, timber rot and fungal attack are associated with high moisture levels. To evaluate the risk of a moisture induced damage resulting in a diminished durability, it is necessary to determine the water storage and transport properties of these porous materials. For a long time, NMR instrumentation was found only in laboratories of institutional and industrial research facilities. In plastics and foodstuff industry, this inherently nondestructive measuring technique is traditionally applied in quality assurance during new product developments and also in routine quality inspections of bulks. Meanwhile, for outside laboratory application and for nondestructive inspection of large objects special NMR devices are available, based on the One-Sided Access (OSA) NMR technique.