Nuclear magnetic resonance, plasma

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

Spectrometric Analysis. Remarkable developments ia mass spectrometry (ms) and nuclear magnetic resonance methods (nmr), eg, secondary ion mass spectrometry (sims), plasma desorption (pd), thermospray (tsp), two or three dimensional nmr, high resolution nmr of soHds, give useful stmcture analysis information (131). Because nmr analysis of or N-labeled amino acids enables determiaation of amino acids without isolation from organic samples, and without destroyiag the sample, amino acid metaboHsm can be dynamically analy2ed (132). Proteia metaboHsm and biosynthesis of many important metaboUtes have been studied by this method. Preparative methods for labeled compounds have been reviewed (133). 

The most common detectors in HPLC are ultraviolet, fluorescence, electrochemical detector and diffractometer. However, despite all improvements of these techniques it seems necessary to have a more selectivity and sensitivity detector for the purposes of the medical analysis. It should be therefore improvements to couple analytical techniques like infrared IR, MS, nuclear magnetic resonance (NMR), inductively coupled plasma-MS (ICP-MS) or biospecific detectors to the LC-system and many efforts have been made in this field. 

Solanky, K.S. et al., Application of biofluid IH nuclear magnetic resonance-based metabonomic techniques for the analysis of the biochemical effects of dietary isoflavones on human plasma profile. Anal. Biochem., 323, 197, 2003. 

Many other analytical techniques can be coupled to mass spectrometers. These so-called hyphenated techniques, like GC-MS and LC-MS, include but are not limited to ICP-MS (inductively coupled argon plasma), SCF-MS (supercritical fluid), NMR-MS (nuclear magnetic resonance) and IR-MS (infrared). 

The components in a mixture separate in the column and exit from the column at different times (retention times). As they exit, the detector registers the event and causes the event to be recorded as a peak on the chromatogram. A wide range of detector types are available and include ultraviolet adsorption, refractive index, thermal conductivity, flame ionization, fluorescence, electrochemical, electron capture, thermal energy analyzer, nitrogen-phosphorus. Other less common detectors include infrared, mass spectrometry, nuclear magnetic resonance, atomic absorption, plasma emission. 

There is abundant evidence to support the concept that the outer layer of plasma lipoproteins is a monolayer of polar lipids (phospholipids, mainly phosphatidylcholine, and cholesterol) and apolipoproteins with the hydrophilic aspect of the apolipoproteins and the polar head groups of phospholipids on the surface. The evidence has been reviewed by others [e.g., (S24)] and will not further be examined here. Nuclear magnetic resonance studies on HDL have shown that about 40% of unesterified cholesterol molecules are in the lipoprotein core, and 60% are associated with phospholipid molecules in the surface. Neither surface nor core is saturated with cholesterol (L20). Presumably, unesterified cholesterol is also found in the core of other lipoproteins. 

J. P. F. Tijssen and J. Van Steveninck (1984). Detection of a yeast polyphosphate fraction localized outside the plasma membrane by the method of phosphorus-31 nuclear magnetic resonance. Biochem. Biophys. Res. Comm., 119, 447-451. 

M. P. Williamson, T. F. Havel, and K. Wiithrich, /. Mol. Biol., 182, 295 (1985). Solution Conformation of Proteinase Inhibitor 11A from Bull Seminal Plasma by H Nuclear Magnetic Resonance and Distance Geometry. 

E704 Otvos, J.D., Jeyarajah, E.J. and Bennett, D.W. (1991). Quantification of plasma lipoproteins by proton nuclear magnetic resonance spectroscopy. Clin. Chem. 37, 377-386. 

Otvos JD, Jeyarajah EJ, Bennett DW, Krauss RM. Development of a proton nuclear magnetic resonance spectroscopic method for determining plasma lipoprotein concentrations and subspecies distributions from a single, rapid measurement. Clin Chem 1992 38 1632-8. 

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