Nuclear magnetic resonance microprobes

The identification, using analytical microprobe and solid-state magic-angle nuclear magnetic resonance (NM techniques, of aluminosilicate deposits in the cores of the pathognomic senile plaques in the brains of Alzheimer subjects (Candy et al., 1986) has prompted widespread scientific and public concern, and controversy with regard to the possible aetiological role of environmental aluminium and aluminosilicates in senile dementia (Walton, 1991). 

G. E. Martin, Microprobes and methodologies for spectral assignments applications, in Encyclopedia of Nuclear Magnetic Resonance, D. M. Grant and R. K. Harris, eds.. Advances in NMR, Vol. 9, Wiley, Chichester, 2002, 98-112. 

Online coupling of HPLC with nuclear magnetic resonance spectroscopy (NMR) has proved useful for a wide range of applications. The shortcoming of suppression of eluent signals can be circumvented by use of capillary separation technique. In this mode detection cells with internal volumes in the nanoliter scale and miniaturized probe heads have been developed by Albert et al. in Tuebingen. The system can be used in either HPLC, CE, or CEC, and consists of a capillary inserted into a 2.5 or 2.0 mm NMR microprobe equipped with a Helmholtz coil. In experiments, a capillary mbe of 315 /rm can create a detection volume of 900 nl. The flow rate of the capillary... 

Birch NJ, Thomas GMH, Hughes MS and Gallicchio VS (1995b) Intracellular lithium Studies using Li nuclear magnetic resonance spectroscopy in erythrocytes, hepatocytes, and fibroblasts. J Trace Microprobe Techn 13 65-80. 

Nuclear magnetic resonance (NMR) spectrometers offer spectral capabilities to elucidate polymeric structures. This approach can be used to perform experiments to determine comonomer sequence distributions of polymer products. Furthermore, the NMR can be equipped with pulsed-liied gradient technology (PFG-NMR), which not only allows one to determine self-diffusion coefficients of molecules to better understand complexation mechanisms between a chemical and certain polymers, but also can reduce experimental time for acquiring NMR data. Some NMR instruments can be equipped with a microprobe to be able to detect microgram quantities of samples for analysis. This probe has proven quite useful in GPC/NMR studies on polymers. Examples include both comonomer concentration and sequence distribution for copolymers across their respective molecular-weight distributions and chemical compositions. The GPC interface can also be used on an HPLC, permitting LC-NMR analysis to be performed too. Solid-state accessories also make it possible to study cross-linked polymers by NMR. 

To date, the diffusion coefficient of a solute in a gel has been determined by the membrane technique, magnetic gradient nuclear magnetic resonance (NMR) spectroscopy, and fluorescence polarization relaxation. Compared to these techniques, the characteristics of the method described in this section include (1) the information obtained by this method is the value near the electrode and the electrode itself acts as a microprobe (2) the diffusion coefficient and disfribution coefficient of the solute can be simultaneously determined (3) not only the gel at equilibrium state but also a non-equilibrium state gel can be studied and (4) relatively simple apparatus can be used to make measurements. Future developments that will build on these advantages is desired. 

Riddell FG (1998) Studying biological lithium using nuclear magnetic resonance techniques. Journal of Trace and Microprobe Techniques 16 99-110. 

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