Process NMR Instrumentation

Solid hydrocarbon materials are not observable in process NMR instruments. In order to be observed the molecules under analysis must be entirely in the liquid state and must be above a nominal viscosity threshold. In heavy or waxy petroleum streams the samples must be heated to approximately 80 °C to lower viscosity and ensure melting and solubility of waxy components. 

The LC-NMR instrument is a very attractive analytical tool in that it has the potential to provide a great deal of data detailing many structural features in an inline mode. The principle advantage to using hyphenated NMR technology is that in most cases one can collect NMR and MS data on the same sample reducing the possibility of decomposition during the isolation and sample preparation process. 

ST2-PT thus results in a 2D [15N, H]-correlation spectrum that contains only the most slowly relaxing component of the 2D 15N- H multiplet. The data are processed as described by Kay et al. [44] in an echo/antiecho manner. Water saturation is minimized by keeping the water magnetization along the z-axis during the entire experiment, which is achieved by the application of the water-selective 90° rf pulses indicated by curved shapes on the line H. It was reported that on some NMR instruments the phase cycle mentioned above does select the desired multiplet component. On these instruments, the replacements of S, with S, = y, x for the first FID and 9, =... 

NMR offers many unique advantages that other methods cannot provide in spite of some limitations. Biopharmaceutical product development will certainly benefit from including NMR as an option for solving analytical problems. NMR instrumentation and methodology are constantly being improved. As better and more sensitive NMR techniques become available, the use of NMR as a standard analytical tool in biopharmaceutical process development and validation is expected to increase. 

Computer control of NMR instruments has led to great advances in both data acquisition and processing and has given rise to advanced NMR structural elucidation techniques. One of the the first of these was two-dimensional... 

Off-line processing -for nmr instruments [MAGNETIC SPIN RESONANCE] (Vol 15)... 

In a factory environment NMR instrumentation needs to be robust and possibly mobile for quality and process control at different stages of product development, fabrication,... 

The process of data acquisition results in an FID signal residing in the computer of the NMR instrument. In order to properly set up the acquisition parameters, it is helpful to understand a little about how this is accomplished. We will follow the sequence of events involved in the acquisition of the raw data for a simple ID ll spectrum on a 200-MHz instrument through a simplified diagram of the spectrometer ... 

This picture shows atypical NMR instrument. The extremely powerful superconducting magnet is shown on the left. This model features a robotic arm to change the samples automatically so many spectra can be run overnight. The large box in the centre of the picture is the radio wave generator and receiver. This is much larger than the computer needed to process the data which simply sits on the bench. 

Gas-phase NMR spectroscopy has been used to obtain equilibrium constants and rate constants for many low-energy molecular processes. These data have been used to address questions regarding the relative stability of conformers and tautomers in the gas phase, the kinetics of exchange processes in the gas phase, and the direction and magnitude of solvent effects on these equilibria and processes. Most of the studies have appeared in the last 10 years. Continued progress in NMR instrumentation and techniques as well as considerable recent developments in kinetic theory ensure that the next 10 years will see many novel applications of gas-phase NMR spectroscopy. 

An NMR spectrometer for SNIF-NMR (Fig. 6.17) (site-specific natural isotope fractionation NMR) measurements [226] must be specifically equipped and adapted, e.g. for deuterium analysis by a high field magnet (e.g. 9.4 T, corresponding to 400 MHz ( H) and 61.4 MHz ( H) resonance frequency, or 11.4 T, corresponding to 500 MHz ( H) and 76.8 MHz ( H) resonance frequency), a specifically adapted H-NMR probe with fluorine lock and proton decoupling, highly stable electronics and software for spectra acquisition and data processing/treatment. Instrumental details... 

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