Data evaluation peak height

FIGURE 3 Example of chromatogram obtained after the separation of three compounds shows three Gaussian peaks. Evaluation of the separation is based on the main chromatographic parameters calculated from graphical data, (h Peak height)... 

Results The raw data consisted of peak height ratios of signal internal standard, see data files VALIDl.dat (primary validation m - 0 repeats at every concentration), VALID2.dat (between-day variability), and VALID3. dat (combination of a single-day calibration with several repeats at 35 and 350 [ng/mlj in preparation of placing QC-sample concentration near these values). Fig. 4.29 shows the results of the back-calculation for all three files, for both the lin/lin and the log/log evaluations. Fig. 4.30 shows the pooled data from file VALID2.dat. 

Detection and Linearity. Since the UV-detector measures /St, quantitation by use of peak height measurements puts less stringent demands on the constancy of the flow rate. A fundamental requirement for adequate evaluation of data is that the chromatography is linear. 

To evaluate the crystallinity of the films, Raman spectroscopy is used. A typical Raman spectrum is presented in Fig. 4. Of the crystalline diamond, a narrow peak at a frequency of 1332 cur1 is characteristic, which is caused by the first-order phonon scattering by the crystal lattice. The non-diamond carbon is represented in the spectrum by two diffuse bands at ca. 1350 and 1550 cm-1. When comparing the peaks height, one should keep in mind that the Raman signal is 50 times more sensitive to the non-diamond carbon than to the crystalline diamond [20], In the high-quality diamond films used as electrodes, the non-diamond carbon component rarely exceeds 1%. Raman spectroscopy data have been corroborated by the independent impedance spectroscopy measurements (see below). According to [21], the inner layer of a diamond film is enriched with the admixture of non-diamond carbon as compared to its outer layer. 

The RATIO method table (Table I) includes provision for specifying upper and lower limits of integration for both primary and reference bands with the peak area evaluation procedure. The practical limits of the integration can be determined empirically by evaluating a set of spectra stored on microfloppy disks with varying limits set in the appropriate locations in the method table. Optimum limits can be determined from the calibration plots and related error parameters. The calibration plots shown in Figures 4 and 5 indicate that both evaluation procedures, peak height and peak area provide essentially the same level of precision for the linear least squares fit of the data. The error index and correlation coefficients listed on each table are both indicators of the relative scatter in the data from the least squares fit line. The correlation coefficient is calculated as traditionally defined in statistics. 

Figure 94. Calibration curve of a TLC plate with measurement data for the evaluation of peak heights for cholesterol in hntter and margarine...

In order to estimate the contribution from the main contaminants in the target, the reactions 12C(nB, 140)9Li and 160(nB, 140) 13B have been measured. These measurements have shown that the contribution from both of the above-mentioned reactions to the 140 spectrum does not exceed 5% of the peak height. In order to estimate the yield under the observed bump the phase space contribution has been subtracted from the experimental data. The resulting value of the cross section under the peak is da/dil = 16 nb/sr. Such an evaluation is of course affected by some uncertainty. A 50% error of this estimate is quite possible. The peak has been attributed to the level of particle unstable 6H lying 2.6 0.5 MeV above the 2H+n + n + n mass and having a width of 1.3 0.5 MeV. This value agrees well with that found in, 3). The difference in cross sections can be explained as due to the use of the 3p transfer reaction in our experiment instead of the 2p-n reaction studied in ref.l3). 

Using peak heights in XPS instead of peak areas speeded up the analysis and evaluation of data. A comparison of peak height ratios with peak area ratios on a selected series of samples showed that only a very small error was introduced by using peak heights. The XPS ratio of carbon to tin was calibrated with TMT vapors solidified at the sample stage at -112°C. A conversion... 

If short-term constancy not guaranteed, a data evaluation using peak height should be preferred over peak area. 

The large errors in estimation of Qq for the present data mean that it is not possible to evaluate Lu as a measure of light limitation in this case. Of the methods in Fig. 3, the flourescence peak height is apparently the least sensitive measure, but this is partly related to the fact that there is a residual fluorescence peak at light saturation. It was not possible to obtain an estimate of the sensitivity analysis approach based on the sensitivity to light at constant q (Ljg), though one would expect such a correction to increase the calculated L,. 

Recently, LC techniques were introduced for the evaluation of dyestuffs. They have much higher sensitivity than TLC, the choice of conditions, mobile phase, and columns again depends on the chemical properties of the dyes, and an extraction procedure is also required. The results obtained by LC can be used for quantitative data processing and, by comparison of retention times, peak height or area ratios, and trace impurity detection by its higher sensitivity than TLC, more detailed discrimination of fiber samples is possible. Multi-wavelength detection using a PDA detector is also useful, as described above. 

Quantitation is carried out based on peak heights or peak areas. The statistical data for this method are summarized in Table 8.5. As can be seen from this data, reproducibility of quantitation depends on the kind of data evaluation. The minimum detection limits that are calculated for both chromium species prove that this method is suitable for determining small amoimts of chromium(III) and chromium(VI). 

The next section deals with method validation of quantitative TLC methods. Two questions should, however, be answered prior to discussing the validation experiments namely, whether the statistical evaluation of data elements, such as precision, accuracy, and reproducibility should be calculated on the basis of measured peak heights or peak areas, and whether the internal or external standard methods, or area normalization should be used to yield quantitative results for the assay. Without going into detail, the most important advantages and limitations of peak height and peak area measurements, and those of the different methods of quantification are summarized in Table 4. 

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