Mass spectrometry proton nuclear magnetic resonance

Using mass spectrometry, proton nuclear magnetic resonance ( H NMR), COSY H NMR analysis, and calculation on the relative thermodynamic stability, Tan et al. (1998) identified a novel melatonin metabolite as cyclic 3-hydroxymelatonin. This is the product of reaction of melatonin with HO generated in two different cell-free in vitro systems. Cyclic 3-hydroxymelatonin also existed in urine of both human and rat. When rats were challenged with ionising radiation (800 cGy = LD50 for a one month period), as expected, urinary cyclic 3-hydroxymelatonin was doubled over that of the controls (P = 0.002). 

Shimamura, M., T. Endo, Y. Inoue, and S. Inoue A Novel Neutral Oligosaccharide Chain Found in Polysialoglycoproteins Isolated from Pacific Salmon Eggs. Structural Studies by Secondary Ion Mass Spectrometry, Proton Nuclear Magnetic Resonance Spectroscopy, and Chemical Methods. Biochemistry 22, 959 (1983). 

We have included what we feel are the six currently most popular analytical techniques ultraviolet (UV) spectrophotometry, infrared (IR) spectrometry, proton nuclear magnetic resonance (NMR) spectrometry, mass spectrometry (MS), gas chromatography (GC), and high pressure liquid chromatography (HPLC). As we felt that the quality of data presented was of paramount importance in a reference source, we generated all of our data in our laboratory under uniform, reproducible conditions using state-of-the-art technology and verified chemical standards. 

Figure 1.13 Selected analytical techniques used for metallomics studies. ICP-OES, inductively coupled plasma optical emission spectroscopy, ICP-MS, inductively coupled plasma mass spectrometry LA-ICP-MS, laser ablation ICP-MS XRF, X-ray fluorescence spectroscopy PIXE, proton induced X-ray emission NAA, neutron activation analysis SIMS, secondary ion mass spectroscopy GE, gel electrophoresis LC, liquid chromatography GC, gas chromatography MS, mass spectrometry, which includes MALDI-TOF-MS, matrix-assisted laser desorption/ ionization time of flight mass spectrometry and ESI-MS, electron spray ionization mass spectrometry NMR, nuclear magnetic resonance PX, protein crystallography XAS, X-ray absorption spectroscopy NS, neutron scattering.

FID = flame ionization detection GC = gas chromatography HPLC = high performance liquid chromatography ITMS = ion trap mass spectrometry MS = mass spectrometry PNMR = proton nuclear magnetic resonance TLC = thin-layer chromatography... 

Nomier AA, Abou-Donia MB. 1986. Studies on the metabolism of the neurotoxic tri-ort/20-cresyl phosphate Synthesis and identification by infrared, proton nuclear magnetic resonance and mass spectrometry of five of its metabolites. Toxicology 38 1-13. 

Below we report methodological studies based upon HPLC, GC/FID, GC-MS, LC-MS, matrix-assisted laser desorption ionisation coupled with time-of-flight mass spectrometry (MALDI-ToF/MS), CE, proton nuclear magnetic resonance ( I INMR), RIA and enzymatic colorimetric techniques. 

Several methods are available in the literature for the measurement of aliphatic amines in biological samples [28]. Problems with specificity and separation and cumbersome derivatisation and/or extraction procedures have limited the use of these techniques on a larger scale in clinical practice. The lack of a simple analytical method may have led to an underestimation of the incidence of the fish odour syndrome. For diagnosing the syndrome, an analytical technique should be used that is able to simultaneously and quantitatively measure TMA and its N-oxide in the complex matrix of human urine. Two such methods are currently available for this purpose proton nuclear magnetic resonance (NMR) spectroscopy and head-space gas analysis with gas chromatography or direct mass spectrometry (see below). 

Crystallography, and by 400-MHz, Proton Nuclear Magnetic Resonance Spectroscopy and High-resolution Mass Spectrometry. 183... 

The liquid products were quantified by GC-FID (gas chromatograph with flame ionisation detector) and characterised with GC-MS (gas chromatograph with mass spectrometer). The aromatics content was monitored on-line with a near infrared spectrometer that was calibrated by proton nuclear magnetic resonance spectrometry. 

Two techniques have revolutionized the structure elucidation of natural products in the past eight years in much the same way that mass spectrometry and proton nuclear magnetic resonance (NMR) spectroscopy did... 

Chemical fractionation methods used in this study were gel cFromatography, acid-base neutral solvent partitioning and chromatography on silica gel columns. Identification of compounds was done by gas chromatography/mass spectrometry (GC/MS). Proton nuclear magnetic resonance (PMR) spectroscopy was used to characterize fractions and subfractions which were not amenable to GC/MS analysis. 

There follows a discussion of proton nuclear magnetic resonance ( H NMR), carbon nuclear magnetic resonance ( C NMR), and mass spectrometry (MS) of the Narcissus alkaloids. A list of the different Narcissus alkaloids, their spectroscopic properties, and literature with the most recent spectroscopic data is given in Table X. 

Its composition and structure were further verified by mass spectrometry and proton nuclear magnetic resonance (NMR). 

The reaction products were analyzed chromatographically [high pressure liquid chromatography (HPLC) and size exclusion chromatography (SEC)] and spectroscopically [proton nuclear magnetic resonance ( H NMR) and secondary ion mass spectrometry (SIMS)]. 

These special features are explained by an interaction between the proton and one of the water molecules, which is not merely electrostatic but also covalent. This yields a new chemical species, the hydroxonium ion, HjO. The existence of such ions was demonstrated in the gas phase by mass spectrometry and in the solid phase by X-ray diffraction and nuclear magnetic resonance. The H -H20 bond has an energy of 712kJ/mol, which is almost two-thirds of the total proton hydration energy. 

As active substances are separated and purified they are characterized by a combination of spectroscopic analyses and chemical correlations. Particularly useful spectroscopic analysis techniques are nuclear magnetic resonance (proton and carbon), mass spectrometry and Infra-red and ultraviolet spectrophotometry. 

As part of a mechanistic and synthetic study of nucleophihc carbenes the spirocyclic 4(5/l)-oxazolone 18 has been obtained from benzoyl isocyanate (Scheme 6.1) Thermal extrusion of nitrogen from the 1,3,4-oxadiazoline 14 produced the carbonyl ylide 15 that fragmented via loss of acetone to the aminooxycarbene 16. Spectroscopic data [gas chromatography-mass spectrometry (GC-MS), infrared (IR), proton and C-13 nuclear magnetic resonance ( H and NMR)] of the crude thermolysate was consistent with 18. The formation of 18 was rationalized to result from nucleophihc addition of 16 to benzoyl isocyanate followed by cyclization of the dipolar intermediate 17. Thermolysis of 19 and 21 under similar reaction conditions afforded 20 and 22 respectively, also identified spectroscopically as the major products in the thermolysate. 

A single measurement of a calibration sample can give the concentration of the test solution by a simple ratio. This is often done in techniques where a calibration internal standard can be measured simultaneously (within one spectrum or chromatogram) with the analyte and the system is sufficiently well behaved for the proportionality to be maintained. Examples are in quantitative nuclear magnetic resonance with an internal proton standard added to the test solution, or in isotope dilution mass spectrometry where an isotope standard gives the reference signal. For instrument responses As and /sample for internal standard and sample, respectively, and if the concentration of the internal standard is Cjs, then... 

The structures of vanicosides A (1) and B (2) and hydropiperoside (3) were established primarily by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy techniques and fast atom bombardment (FAB) mass spectrometry (MS).22 The presence of two different types of phenylpropanoid esters in 1 and 2 was established first through the proton (4H) NMR spectra which showed resonances for two different aromatic substitution patterns in the spectrum of each compound. Integration of the aromatic region defined these as three symmetrically substituted phenyl rings, due to three p-coumaryl moieties, and one 1,3,4-trisubstituted phenyl ring, due to a feruloyl ester. The presence of a sucrose backbone was established by two series of coupled protons between 3.2 and 5.7 ppm in the HNMR spectra, particularly the characteristic C-l (anomeric) and C-3 proton doublets... 

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