Sum Peak Method

The sum peak method, if carefully used in the systems accompanied by chemical or biochemical change, is a useful tool for detecting such change and it may also be a convenient method to determine perturbed angular correlation (PAC) parameters mthout complicated electronic circuits. 

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Another subject which will be of interest for those who wish to apply nuclear chemistry for analytical purposes, is the sum peak method . The prindple of this method is based on a perturbed angular correlation (PAC) for two y-emissions in cascade decay from a radioactive nucleus. The emission angle betweoi the two y s has a distribution pattern which reflects the mode of radiative decay, as well as depetuling on the environmental conditions. The sum peak which is seen in a y-ray spectrum as a result of simultaneous detection of the twoy-rays as one event, is therefore influenced by the environments in which the source is placed. In the sum peak method, intendty ratios of the stun peak to the single peak can be used and chan in the ratios due to the environments can be observed. 

These basic relations described above can be utilized in application of the sum peak method to chemical and/or biological sample. 

Yoshihara measured Tb in terbium oxide Tb O, and in terbium chloride solution by the sum peak pair method , and pointed out that the difference of the sum peak intensity ratio between two states could be enlarged by using comparison of a sum peak pair. This method has an advantage that the dependence of the sum peak pair ratio on the soun -detector distance is not as noticeable as that in the ordinary sum peak method. 

The Sum Peak Method Applied to ffiloh [ical Substances... 

The PAC method can be applied to biological substances information obtained by this method is sometimes so unique and valuable that other methods cannot compete with it. The sum peak method based on the principle of PAC b also expected to provide useful information on biological samples. 

Although the sum peak method does not allow the Gj values to be determined as accurately as in ordinary PAC measurements, it has some advantages over the PAC method. Only an aliquot of labeled sutetances is required for the measurement, the measurement is much shorter, and the apparatus needed is much sim der. Future development of this method should be encouraged. 

The sum peak method was studied to determined a PAC parameter of In in hydrochloric add It is dependent on pH, espedally in a 4-14 region. At higher concentrations of hydrochloric acid, however, Gj2 stays at a constant value inspite of formation of an InCl type complex. 

Data Processing. Fraser (21) has shown that, with data measured in array form, each array member may be individually given Lorentz (velocity), polarization and absorption corrections. This avoids the problems incurred in the Photometric Peak Center method and Sum Intensity method in which the corrections are applied as if all intensity is recorded at the peak amplitude position. Fraser (22) has also shown that, by choosing data... 

Solomon (16,has uset a different method to obtain extinction coefficients. Essentially, total hydrogen content from elemental analysis and hydroxyl content from measurements of the area of the 0-H stretching band near 3450 cm were used in conjunction with the peak areas of aliphatic and aromatic bands to obtain a plot from which extinction coefficients can be determined. In principle, this approach appears to be sound, but there are a number of problems. One difficulty, discussed above, is general to all infrared methods that have been employed so far what errors are introduced by summing peak areas over a number of bands, each of which has an individual extinction coefficient, and essentially averaging such coefficients for the total area Other problems involve the correct use of curve resolving techniques and the measurement of hydroxyl groups, which we will now consider in more detail. 

Gaseous fuels may be quite different in composition and therefore no universal analytical method exists. Particularly in process chromatography, only the most interesting compounds are individually determined, to obtain short cycle times. Less important compounds are neglected or determined as a sum peak. There are a number of different analytical methods. 

To sum up, in some instances the proposed tangent method and procedure of systematic error correction allows excluding the necessity of mathematical or chemical resolution of overlapped peak-shaped analytical signals. 

A rough estimate of the concentrations of components in a mixture can be obtained using peak areas. This method assumes that the area percent is approximately the weight percent. The area of each peak is divided by the sum of the areas of all peaks,... 

Radial distribution curves for carbon disulfide and carbon oxysulfide (treated by the usual method by Cross and Brockway11) are shown in Fig. 5. For carbon disulfide the maxima of the two peaks occur at 1.60 and 3.07 A. In this symmetrical linear molecule the C-S distance is just one-half the S-S distance the values found deviate from this ratio by 4%. Similarly in carbon oxysulfide the sum of two interatomic distances equals the third. The values C-S = 1.60 A. and O-S = 2.70 A. given by the two maxima differ by 1.10 A. 

For manual optimization methods the peak separation function, P, is easy to determine and can be calculated as shown in Figure 4.30 (479). The chromatographic response function for the chromatogram is then simply the sum of the In P values for the n adjacent peak pairs. 

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