Peak measurement analysis

Table 1 also contains some peak measurement/analysis parameters that might be investigated in a robustness test (see Section III.C). ° However, except from the detection wavelength, these parameters are hardly ever evaluated in a robustness test, even though they can have a large influence on the electropherogram. 

Operational and environmental factors Peak measurement/analysis parameters... 

FIGURE 3 Two electropherograms from one run, recorded with different settings for peak measurement/analysis parameters. 

It is seen that there is not a great difference between the use of peak heights or peak areas for quantitative analysis, except possibly for very early peaks, where the results seem to indicate that peak height measurements might be more precise. However, it again must be emphasized that the measurements made by Scott and Reese were overall precision measurements that will include all variations in the chromatographic system. The difference between the two methods of measurement may well be significant, but the absolute values for precision will not, by any means, be solely dependent on the method of peak measurement. 

With techniques of peak measurement in hand the next important step in quantitative analysis is to convert the size of the peak into some measure of quantity of the particular material of interest. In some fashion this involves chromatographing known amounts of the materials to be analyzed and measuring their peak sizes, then, depending on the technique to be used, relating the unknown peaks to the known amounts through peak size. 

In addition to evaluation of line widths and peak separations, analysis of T values and spin saturation transfer can be performed to access a wide range of timescales. Under conditions of slow exchange between forms A and B and upon irradiation at vb, the time constant associated with state A (ta) can be determined from the measured T of nucleus A in the presence of exchange and the T of nucleus A in the absence of exchange ... 

The resolution of a pair of closely eluted solutes is usually defined as the distance between the peaks, measured in units of the average standard deviation of the two peaks. However, it is necessary to decide the degree of separation that constitutes adequate resolution for accurate quantitative analysis. In figure 1, five pairs of peaks are shown, separated by values ranging from 2a to 6a, the area of the smaller peak being half that of the larger peak. It is clear, from figure 1, that... 

More precise information about the details of such anomalous radical eliminations resulted from the detailed investigation of labelled compounds of the general structure 45 51. Here the combined application of different methods e.g., appearance potential measurements, peak shape analysis, CA studies, kinetic energy release) established that the cleavage of a heteroatom-carbon bond can take place via two fundamentally different mechanisms ... 

The OH eliminations from ortho substituted aldoximes, 111 (X = CH2, NH, O) may at least partially be the result of a hydrogen transfer/cyclization process, whereby the heterocycles 112 are formed117. A peak shape analysis as well as the investigation of 2H labelled derivatives indicates that in addition to 112 the protonated isocyanide, 113, is formed. This fragment, however, is generated without any measurable interaction with the ortho substituent. 

We have just seen how measuring these breadths enables us to quantify the defects. This analysis method implies the fitting of the peaks and therefore requires us to define a priori the shape of the diffraction peaks. Berlaut [BER 49] followed by Warren and Averbach [WAR 50, WAR 55, WAR 69] showed that with the help of a Fotrrier series decomposition of the peak profiles, any material with voltrme structrrral defects can be analyzed without having to make hypotheses on the shape of the peaks. This analysis, which we will now describe, when it can be implemented, remairts even today one of the most exterrsive ways to study microstructrtral effects based on the profiles of the diffraction peaks. 

Doublets, higher aggregates, and cell debris can be excluded from analysis by using correlated area/peak measurements of DNA content histograms (7). 

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