Nuclear magnetic resonance reference signal

The nuclear magnetic resonance (NMR) spectra (300MFIz) of both the compound 10 and 11 was recorded in dimethyl sulfoxide (DMSO-r4) and CDCI3. The compound 10 in its H NMR spectrum showed a singlet signal at 5 5.32 due to the two NH protons, whereas compound 11 showed the presence of two NH protons at 6 6.80 <1989JOC3062>. For information on spectral studies of the compounds 1-5, refer to CHEC-II(1996) <1996CHEC-II(8)707>. 

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... 

A 400 MHz nuclear magnetic resonance (NMR) method for the identification of rocuronium bromide was reported by Fielding [10]. The aH spectra were referenced to an internal TMS standard, while the solvent signals at 77.0 ppm (CDCI3) or 39.6 ppm (DMSO-dg) were used as references for the 13C data. Based on the NMR spectra, it was concluded that... 

Incorporation studies of C-labeled precursors require extensive nuclear magnetic resonance (NMR) measurements. The signals of C-NMR-spectra of the analyzed metabolites must be assigned fully. The C-NMR spectra of the reference compound of natural abundance (1.1%) and of the labeled metabolite must be recorded in the same conditions. A comparison between the relative signal intensities of the two spectra indicates that the carbon atom is labeled and indicates the magnitude of the isotope enrichment. 

Nuclear magnetic resonance analysis with double and triple resonance was used to elucidate the structure as 3, 4 -dideoxykanamycin B 2"-adenylate. The spectrum of the inactivated 3, 4 -dideoxykanamycin B in deuterium oxide at pH 8.0, with tetramethylsilane as the external reference standard (8 =0), showed signals at 8 8.63 and 8.85 attributable to the adenine-ring protons, and at 8 6.53, 5.28, 4.98, 4.83 and 4.6 (H-2) the latter were assigned to the D-ribose-ring protons by successive doubleresonance experiments, and by comparison with disodium 5 -adenylate in deuterium oxide. Therefore, these observations confirmed the presence of one molecular proportion of 5 -adenylic acid in the molecule. Irradiation at 8 5.45 (7 3.6, H-1") caused the complex signal at 8 4.3 (H-2")... 

The carbon-13 nuclear magnetic resonance spectrum of lovastatin shown In Figure 3 was obtained using a Bruker instruments Model AM-300 NMR spectrometer and an approximately 4% w/v solution of the compound In deuterochloroform. Signal assignments are tabulated below and refer to the numbered structure shown in Section 4.2... 

Walker, T. E., R. E. London, T. W. Whaley, R. Barker, and N. A. Matwiyoff Carbon-13 Nuclear Magnetic Resonance Spectroscopy of (1- C) Enriched monosaccharides. Signal Assignments and orientation dependance of geminal and vicinal Carbon-Carbon and Carbon-Hydrogen Spin-Spin coupling constants. J. Amer. Chem. Soc. 98,5807 (1976) and references cited therein. 

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