Peak analysis width

To use PAIRS, the scientist was required to supply the system with peak intensity, width, and position information derived from the unknown compound s spectrum, as well as information concerning the sample state (e.g., solvent, neat, mull). In addition, the scientist was allowed to indicate the presence or absence of given atom types in the empirical formula of the unknown compound. Since the goal in performing a PAIRS interpretation was to provide the user with a functional group analysis, the results of an early PAIRS interpretation were limited to a numerical indication of the likelihood of presence or absence for a given functionality. An example of the interpretation results provided by an early version... 

When coronene, C24H12, (C) is treated with thallium(III) trifluoroacetate as oxidant under dried nitrogen atmosphere in l,l,l,3,3,3-hexafluoropropane-2-ol solvent coronene radical species are formed. Depending on the sample preparation the ESR spectra are dominated by the monomeric ion (C)", or are superpositions of spectra due to ( ) and the dimeric ion (C2) or even the trimeric ion (Cs). A stick-plot analysis of the spectrum of the nearly pure monomer is part of Exercise E3.5. It is also possible to accurately measure the hyperfine coupling constant (0.0766 mT for 24 H) and the corresponding peak-peak line-width (AHpp = 0.009 mT) for the ( 2) species in Eig. 3.7(b), since the lines are quite sharp, compared to those from the monomer. The line shape of ( 2)" can therefore be obtained by simulation, that of ( ) from experiment The component spectra are then superimposed in a ratio appropriate for the experimental spectrum. This ratio is usually obtained by manual adjustment for best visual agreement with the experimental line shape in the present... 

From analysis of lanthanide (Ln " ") tetraazatetrakis-phosphinato and phosphonato complexes (42)," self-association was observed in aqueous solution for both the [Ln(DOTP -OEt)] and [Ln(DOTP -OBu)] ester complexes through examination of their P-NMR-, EPR-, and luminescence-spectroscopy, as well as vapour-pressure osmometry data. The X-band EPR spectra were recorded for [Gd(DOTP -H)] , [Gd(DOTP -Et)] , [Gd (DOTP -OEt)], and [Gd(DOTP -OBu)] complexes in the 1-10 mmol/L concentration range at pH 7.0 and 298 K, which gave approximate Lorentzian lines with a g value around 2.0 and variable peak-to-peak line widths, (d/fpp), dependent on the concentration of the complexes. An increase in the line width was observed in all cases but was much larger for [Gd(DOTP -OEt)] increasing from 40.5 to 80.0 mT. In the phosphinato complex [Gd(DOTP -H)] , no increase was observed with A//pp around 26 mT, indicating that the... 

The peaks at higher r values gradually disappeared with an increase in temperature and pressure, indicating the breaking of the ice-like hydrogen-bonded tetrahedral structure of water. The peak analysis was performed for the first peak around 200 00 pm of the radial distribution function in the form of D(r)/4TT/ pQ, and the peak was de-convoluted into two peaks, I and n, as seen in Fig. 12. The structure parameters, r, n and half-width at the half-height of the peak, cr, which corresponds to the mean-square amplitude of bonds, are summarized in Table 2. 

The peak-analysis is done by fitting a bivariate polynomial to the cap of the peak in order to determine its position and the standard deviations that describe the peak widths in equatorial and meridional directions [2, 9]. Let the y-direction be the meridian, in analogy to the correlation method, a ROI is defined by the user. Inside this ROI the algorithm searches for the peak. The 2D peak is fitted to a 2D function. Figure 3.6 demonstrates the fit of the long period peak by a bivariate quadratic polynomial. In order to assure numerical stability of the regression module on digital computers, the maximum intensity in the measured peak data is normalized to 1. 

In a chromatographic analysis of lemon oil a peak for limonene has a retention time of 8.36 min with a baseline width of 0.96 min. y-Terpinene elutes at 9.54 min, with a baseline width of 0.64 min. What is the resolution between the two peaks ... 

A chromatographic analysis for the chlorinated pesticide Dieldrin gives a peak with a retention time of 8.68 min and a baseline width of 0.29 min. How many theoretical plates are involved in this separation Given that the column used in this analysis is 2.0 meters long, what is the height of a theoretical plate ... 

Quantitative Calculations In a quantitative analysis, the height or area of an analyte s chromatographic peak is used to determine its concentration. Although peak height is easy to measure, its utility is limited by the inverse relationship between the height and width of a chromatographic peak. Unless chromatographic conditions are carefully controlled to maintain a constant column efficiency, variations in... 

Crystallite Size. From the width of the peaks the computer can determine the size of the crystaUites in the sample. The smaller the crystaUite size, the broader are the diffraction peaks. This kind of analysis is important for determining particulate size of certain materials (eg, sUica) where a range of crystaUite size may be a health hazard if inhaled into the lungs. 

Gas chromatographic analysis at 79° using a flame detector in conjunction with a 183 x 0.32 cm. stainless-steel column containing Dow-Corning 550 fluid on silanized support gave peaks for l-bromo-3-chloropropane (6.5 minutes) and 6-chloro-2-hexyne (9.3 minutes) whose areas were shown to be proportional to the mole fractions. The latter were determined by integration of the expanded (50 Hz sweep width)... 

As mentioned above, the interpretation of CL cannot be unified under a simple law, and one of the fundamental difficulties involved in luminescence analysis is the lack of information on the competing nonradiative processes present in the material. In addition, the influence of defects, the surface, and various external perturbations (such as temperature, electric field, and stress) have to be taken into account in quantitative CL analysis. All these make the quantification of CL intensities difficult. Correlations between dopant concentrations and such band-shape parameters as the peak energy and the half-width of the CL emission currently are more reliable as means for the quantitative analysis of the carrier concentration. 

To day peak widths are rarely used in chromatographic analysis except for the purpose of calculating peak areas. Peak widths, however, can provide a means of measuring the diffusivity of a solute which is a function of the molecular weight. Consequently, if a reliable relationship between diffusivity and molecular weight can be identified, then the molecular weight of the solute can be assessed. Peak widths of solutes eluted from an open tube can give very precise values of diffusivity. There are a number of equations that purport to relate diffusivity to... 

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