Signal intensities, relative

E/Z ratios were determined from relative signal intensities in the F NMR spectrum. 

In a study with 3 EMS patients the relative signal intensities in proton spectra recorded at an echo time of 50 ms with a repetition time of 2 s were quantitatively compared with healthy controls. It was evident that the muscle specific signals from TMA and Cr are relatively low in EMS patients (TMA 0.20-0.43% in the patients and 0.47-0.68% in the controls creatine 0.32-0.60% in the patients and 0.48-0.77% in the controls) probably indicating changes of concentrations and altered chemical surroundings of TMA and Cr in the myoplasm of the diseased cells. The overall lipid signal was found to be... 

It is not usually possible to integrate routine C spectra directly unless specific precautions have been taken. However with proper controls, NMR spectroscopy can be used quantitatively and it is a valuable technique for the analysis of mixtures. To record C NMR spectra where the relative signal intensity can be reliably determined, the spectra must be recorded with techniques to suppress the Nuclear Overhauser Effect and with a long delay between the acquisition of successive spectra to ensure that all of the carbons in the molecule are completely relaxed between spectral acquisitions. 

B. "Relative" Signal Intensities (Short Data Collection Times)... 

The use of MALDI-MS for the measurement of low molecular mass compounds is widely accepted now [61], but quantification remains problematic. The main problem is the inhomogeneous distribution of the analytes within the matrix [62]. This leads to different amounts of ions and therefore to different signal intensities at various locations of a sample spot. The simplest and most effective way to overcome this problem is the use of an appropriate internal standard [63]. The use of deuterated compounds with a high molecular similarity to the analyte as internal standards leads to a linear correlation between relative signal intensities and relative amount of the compound to be quantified (Fig. 4b) [64]. Using this approach it is possible to quantitate substrates and products of enzyme catalyzed reactions. Two examples were shown recently by Kang and coworkers [64, 65]. The first was a lipase catalyzed reaction which produces 2-methoxy-N-[(lR)-l-phenylethyl]-acetamide (MET) using rac-a-... 

Fig. 4. a rac-Phenylethylamine (PEA) and 2-methoxy-J T-[(li )-l-phenylethyl]-acetamide (MET) are substrate and product in a lipase catalyzed transesterification, b Linear relationship between relative signal intensities in MALDI-MS and the relative concentrations of PEA/d5-labeled PEA. c Comparison of decrease in PEA during enzymatic conversion as measured by quantitative MALDI-MS and gas chromatography (GC)... 

A mutarotational equilibration is demonstrated in Fig. 5.5 by the time dependent 13C NMR spectrum of a solution of D-glucose. Initially, the solution contains almost pure a-D-glucose, but the signals at lower field corresponding to the /i-anomer soon appear. At equilibirium, the relative signal intensities indicate that the /i-anomer is favored (60% P, 40% a Fig. 5.5) [685],... 

Sample preparation method Relative signal intensity ... 

Draw formulae for all the isomers of dichloro cyclopropane and predict the relative signal intensities in their H NMR spectra. Compare your answer with results obtained from a determination of the symmetry elements and point groups. 

The two diastereomers of 1,3,5-trichlorocyclohexane have relative signal intensities of 1 1 1 and 2 2 2 1 1 1 in their lU NMR spectra, respectively. Which set of signals corresponds to which isomer ... 

Assignments of intensity are made for elements with multiple isotopes in a prioritized order that depends on the relative signal intensities observed. The assignments are evaluated and adjusted if necessary for elements with overlapping isotopes. 

Kovarsky et al have used the SIMS method to determine the mole fraction in InGaN [8], Their technique is based on a comparison of the relative signal intensities of CsM+ (M = In, Ga) and does not require reference samples. The SIMS results were independently confirmed by XRD, energy dispersive X-ray fluorescence spectroscopy, EPMA and SNMS, and the absolute value of the InN mole fraction has a relative accuracy <15%. 

The signals for carbons 5 (of which there are two) and 6 (of which there is one) are so close that assignments based on calculated chemical shifts alone are not likely to be 100% reliable. But notice that relative signal intensity is also consistent with the above assignment. 

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