Liquid chromatography-nuclear INDEX

In addition to the above prescriptions, many other quantities such as solution phase ionization potentials (IPs) [15], nuclear magnetic resonance (NMR) chemical shifts and IR absorption frequencies [16-18], charge decompositions [19], lowest unoccupied molecular orbital (LUMO) energies [20-23], IPs [24], redox potentials [25], high-performance liquid chromatography (HPLC) [26], solid-state syntheses [27], Ke values [28], isoelectrophilic windows [29], and the harmonic oscillator models of the aromaticity (HOMA) index [30], have been proposed in the literature to understand the electrophilic and nucleophilic characteristics of chemical systems. 

SD standard deviation SDE simultaneous distillation extraction SDS sodium dodecyl sulfate SFC solid fat content SFI solid fat index SHAM salicylhydroxamic acid SIM selected ion monitoring SNIF-NMR site-specific natural isotope fractionation measured by nuclear magnetic resonance spectroscopy SP-HPLC straight-phase high-performance liquid chromatography... 

Liquid chromatography (LC) has already been described and is an excellent separation technique for compounds that are nonvolatile, thermally unstable and relatively polar in nature. The usual detectors for LC are based on refractive index, conductivity, amperometry, light scattering, UV and fluorescence, all of which have been discussed in Section 3.2. However, sometimes it is desirable to have a more powerful detector attached to an LC instrument and, as such, the following combinations are possible LC-infrared spectrometry, LC-atomic spectrometry, LC-inductively coupled plasma-mass spectrometry, LC-mass spectrometry, LC-UV-mass spectrometry, LC-nuclear magnetic resonance and even LC-nuclear magnetic resonance-mass spectrometry. 

When simple liquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

For some liquid feedstocks such as naphthas, the componential composition is often obtained by gas chromatography (GC) and/or mass spectrometry (MS). For gas oils or heavier feedstocks, it is impossible to obtain the desired analysis. Paraffins, olefins, naphthenes, aromatics (PONA) grouping is sometimes used as a means of feed characterization. For gas oils. Bureau of Mines Correlation Index (BMCI) has been used as a parameter for feed characterization. Since the 1980s, nuclear magnetic resonance (NMR) spectroscopy has been used to characterize heavy feedstocks. 

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