Nuclear magnetic resonance operation

Boelens, R., et al. Complex of lac repressor headpiece with a 14 base-pair lac operator fragment studied by two-dimensional nuclear magnetic resonance. /. Mol. Biol. 193 213-216, 1987. 

The proton nuclear magnetic resonance (NMR) spectra of primaquine diphosphate was obtained using a Bruker instrument operating at 300, 400, or 500 MHz. 

Modern spectroscopy plays an important role in pharmaceutical analysis. Historically, spectroscopic techniques such as infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used primarily for characterization of drug substances and structure elucidation of synthetic impurities and degradation products. Because of the limitation in specificity (spectral and chemical interference) and sensitivity, spectroscopy alone has assumed a much less important role than chromatographic techniques in quantitative analytical applications. However, spectroscopy offers the significant advantages of simple sample preparation and expeditious operation. 

A systematic development of relativistic molecular Hamiltonians and various non-relativistic approximations are presented. Our starting point is the Dirac one-fermion Hamiltonian in the presence of an external electromagnetic field. The problems associated with generalizing Dirac s one-fermion theory smoothly to more than one fermion are discussed. The description of many-fermion systems within the framework of quantum electrodynamics (QED) will lead to Hamiltonians which do not suffer from the problems associated with the direct extension of Dirac s one-fermion theory to many-fermion system. An exhaustive discussion of the recent QED developments in the relevant area is not presented, except for cursory remarks for completeness. The non-relativistic form (NRF) of the many-electron relativistic Hamiltonian is developed as the working Hamiltonian. It is used to extract operators for the observables, which represent the response of a molecule to an external electromagnetic radiation field. In this study, our focus is mainly on the operators which eventually were used to calculate the nuclear magnetic resonance (NMR) chemical shifts and indirect nuclear spin-spin coupling constants. 

The C-NMR spectrum ofindinavir sulfate, shown in Figure 13, was obtained using a Bruker Instruments model AMX-400 nuclear magnetic resonance spectrometer operating at a frequency of 100.55 MHz as an approximate 4.16 % w/v solution in deuterium oxide. The 67.4 ppm resonance of dioxane was used as an external reference standard. Peak assignments are found in Table 8, and make use of the numbered structural formula given previously [11]. 

Normalization, 6 Normal modes, 240-244 of benzene, 438-439 of boron trifluoride, 281, 290 of carbon dioxide, 242, 248, 262, 265 of ethylene, 291 and group frequencies, 266-268 IR active, 457 Raman active, 457 and symmetry, 246-249,430-439 of water, 431-437 Normal operator, 108 Nuclear g factor, 3 24 Nuclear magnetic moments, 323-325 Nuclear magnetic resonance, 129-130, 323-366... 

Nowadays, 3 P-NMR (nuclear magnetic resonance) is sometimes proposed as a better alternative, because this technique requires only a minimum amount of sample pretreatment (12-14). In our opinion, its high investment cost and need for highly qualified operators will cause P-NMR to remain a research technique rather than a quality-control method. However, being an absolute technique, P-NMR seems ideally suited to certify the composition of standard solutions whose quality largely determines the accuracy of both TLC and HPLC results (15,16). 

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