Mass difference plot

Fig. 19. Shear stress and first normal stress difference plotted as a function of shear rate for different molar masses, and b at different concentrations of polystyrene in toluene... 

As an example of the form of the information that may be derived from a pyrolysis-MS, Figure 26 [69] shows the structure of the polycarbonate (PC) and the EI-MS spectra of pyrolysis compounds obtained by DPMS of poly(bisphenol-A-carbonate) at three different probe temperatures corresponding to the three TIC (total ion current) maxima shown in Figure 27(b) Figure 27 compares the MS-TIC curve with those obtained from thermogravimetry. (The TIC trace is the sum of the relative abundances of all the ions in each mass spectrum plotted against the time (or number of scans) in a data collection sequence [70].)... 

Figure 3. Relative mass differences for elements that have two or more isotopes, cast as Am/m, where Am is the unit mass difference (Am = 1), and m is the average mass of the isotopes of that element, as a function of atomic number (Z). Note that Am/m is reported in percent, and is plotted on a log scale. Elements that are discussed in this volume shown in large black squares. Other elements that have been the major focus of isotopic studies shown in gray diamonds, and include H, C, O, and S. The relatively large mass differences for the light elements generally produce the largest isotopic fractionations, whereas the magnitude of isotopic fractionation is expected to markedly decrease with increasing mass.

When each peak in the reference spectrum has been matched with a corresponding peak in the spectrum acquired, the mass difference is calculated for each pair of peaks (see Section 3.1.2). These mass differences are plotted as points on a graph each data point has the mass of the acquired peak as its x coordinate, and the mass difference above as its coordinate, and a smooth curve is drawn through the points (Figure 13.10) [5]. The polynomial order parameter controls the type of curve that is drawn and can be set to any value between 1 and 5 ... 

Figure 13.10. Plot of the mass difference between reference spectrum and acquired spectrum. MSI static calibration, 28 matches of 28 tested references, SD = 0.0465. (Courtesy of Micromass Quattro LC.)...

A polymer, even in its pure state, corresponds to a distribution of macromolecules with different masses. Exclusion chromatography can determine the distribution in molecular weights and the most probable mass and the mean mass. For this type of application, a calibration curve is made using macromolecules of known masses by plotting the retention times (or volumes) on the abscissa and the logarithms of the molecular masses on the ordinate. As can be seen in Fig. 7.5, a linear relationship is obtained. Using this graph, an approximate mass of the unknown can be determined by use of the retention time (volume). This assumes that the mass and the molecular volumes are directly related. 

Fig. 3 depicts a MALDI-MS spectrum (expanded plot) of linear siloxanes with methyl and hydroxyl end groups. It shows that linear siloxanes with methyl end groups may be differentiated from diols (the molar mass difference is 4 daltons) in the range 1.000-1.500 Da. Of course, there is no baseline separation between these specimen because of silicon and carbon isotope distribution in silicon-organic compounds. Smaller amounts of cyclosiloxanes, also present in the sample, are clearly separated from methyl end-capped components. 

FIGURE 6.6 The differences of calculated sum of binding energies by Scofield [26] and Rodrigues et al. [27] in units relative to the total mass are plotted versus the number of electrons left in the ion. For a colour reproduction of this figure see the colour plate section, near the end of this book. 

Figure 22 Importance of nebulizer choice in aerosol delivery via mechanical ventilation. The breathing pattern was fixed and inhaled mass (%) is plotted against time for four different nebulizers. (From Ref. 27.)...

Deduced from plots of mass difference (see Table I) vs average fuel density. 

Deduced from plots of mass difference (see Table I) ys critical mass. Corrected for effect of mounts and interstitial grease and oil loading. ... 

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