Peak analysis

These spacings correspond to cationized fragments with the general composition [SixOyHz]+. The results of the peak analysis prove that the uppermost monolayer of the surface film consists of totally hydrolyzed polymeric siloxanes. There is evidence that these fragments appear as ring- and cage-like silsesquioxane cations (Fig. 2) ... 

General CE problems (e.g., wall interactions of proteins) have been discussed elsewhere. All ACE techniques working with a ligand added to CE buffer (classical ACE, Hummel-Dreyer principle, vacancy peak analysis) imply the potential problem that any continuously infused matrix can increase background noise and, even worse, deteriorate the ionization of the analyte due to competition. 

Long et al. [87] employed an ANN approach for the analysis of low-resolution XRF spectra. Instead of peak analysis and fitting the experimental results to a mathematical function as is common when conventional algorithms are used, the ANN method takes the spectrum as a whole, comparing its shape with the patterns learnt during the training period of the network. 

The equivalence ratio can be calculated from the Mark-Houwink coefficient, K, of component homopolymers. The composition distribution in the chromatogram of a block copolymer is negligible. The peak point of a block copolymer chromatogram corresponds to the average structure of the polymer. Thus, analysis of block copolymers is reduced to analysis of the peak point. Analyses of anionic block copolymer structures have been successfully accomplished by this peak analysis technique with the aid of equivalence ratio. 

Figure 5.3. Peak analysis of liquid chromatogram. The chromatographic separation of a protein sample is analyzed with PeakFit using Haarhoff-Van der Unde (HVL) function by AutoFit Peaks I menu.

The obvious benefit of the quadrupole ion trap is that it is an ion storage device. Therefore, ions can be both accumulated and stored for extended periods. Accumulation can occur over a continuous ionization event or over multiple pulsed ionization periods. When used with pulsed ionization sources, duty cycle, defined in terms of sample utilization, can be as high as 100%. Because a broad range of atomic ions can be stored simultaneously, the quadrupole ion trap is a promising analyzer for transient peak analysis. 

In elution systems like chromatography, nc can be significantly larger than the value indicated in Eq. 5.61 because each successive volume sweeping the column can bring forth and resolve a new group of peaks. Analysis shows that the peak capacity (for adjacent peaks at Rs = 1) is approximately [19]... 

The XPS (X-ray Photoelectron Spectroscopy) and IR analyses have been described in detail elsewhere [14], Here, only some important facts are summarized. The XPS data acquisition was performed with a SAGE 150 Spectrometer (Specs, Berlin, Germany) using a non-monochromatized MgK or AIKq, radiation with 12.5 kV and 250 W settings at a pressure 10-7 Pa in the analysis chamber. XPS spectra were acquired in the constant analyzer energy (CAE) mode at 90° take-off angle. Peak analysis was performed using the peak fit routine from Specs. 

Measurement Procedure. IGC measurements were started after the thermal and flow equilibrium in the column were stable (2 to 3 h). To facilitate rapid vaporization of the probe (0.01 yL), the injector temperature was kept 30°C above the boiling point of the probe. Measurements were made at five carrier gas flow rates. The retention volumes of six injections for each probe and twenty injections of the marker (H2) at a given flow rate were averaged. The values obtained were extrapolated to zero flow rate to eliminate the flow rate dependence of the retention data. The net retention time (tR) is defined as the time difference between the first statistical moment of the solvent peak and that of the marker gas. Thus, tR was calculated by an on-line computer statistical peak analysis rather than the retention time at the peak maximum (tp,maY). This eliminated inaccuracies arising from slight peak asymmetry, which occurs even for inert and well-coated supports. The specific retention volumes (Vg°) derived from tR and tR max differed by as much as 5% for small retention times and slightly skewed peaks (11,12). 

Figure 13.3 Adsorption isotherms of resorcinol, catechol, and phenol on Lichrosorb RP-18 measured by FA and by system peak analysis. Reproduced with permission from S. Levin, S. Abu-Laji, S. Golshan-Shirazi, G. Guiochon, J. Chro-matogr. A, 679 (1994) 213 (Fig. 3).

Peak by peak analysis is widely used in X-ray diffraction and significant developments in digital calculations have made it possible to define very precisely the actual peak profiles. It sometimes happens, however, that the peaks overlap too much for it to be possible to separate their contributions. It then becomes necessary to provide additional information which makes it possible to correlate either the relative positions of the different peaks or their intensities. This is referred to as whole pattern fitting. 

FIGURE 2.3. Two electropherograms, recorded with different settings for peak measurement/peak analysis parameters. Experimental conditions are identical. Adapted from Reference 19. 

Therefore through peak-matching and metastable peak analysis, it is possible to determine with great confidence the structure of the ions. However the latter procedure has become a little out-dated when compared with the new and more efficient techniques (e.g. MIKE or reversed Nier-Johnson geometry), described in specialized monographs. 

Allows for advanced peak analysis of complex heating and cooling curves. 

The elements (and associated peaks) shown in Figure 5 are the optimal peaks for monazite and/or xenotime analysis, based on avoidance of interferences with other peaks. Any factor influencing the peak count rate will ultimately affect the MDL. Several REE La peaks are subject to inter-element interference (see below) and therefore neglected in favor of LP peak analysis, despite the higher MDL associated with LP peaks. 

Can authenticate some compounds (vanillin). Can be combined with GC for peak-by-peak analysis. 

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