Resolution 50 % valley

Resolution 10% valley definition, m/Am. Let two peaks of equal height in a mass spectrum at masses m and m/Am be separated by a valley that at its lowest point is just 10% of the height of either peak. For similar peaks at a mass exceeding m, let the height of the valley at its lowest point be more (by any amount) than 10% of either peak height. Then the resolution (10% valley definition) is m/Am. It is usually a function of m therefore, m/Am should be given for a number of values of m. 

A variety of models have been developed to study acid deposition. Sulfuric acid is formed relatively slowly in the atmosphere, so its concentrations are beUeved to be more uniform than o2one, especially in and around cities. Also, the impacts are viewed as more regional in nature. This allows an even coarser hori2ontal resolution, on the order of 80 to 100 km, to be used in acid deposition models. Atmospheric models of acid deposition have been used to determine where reductions in sulfur dioxide emissions would be most effective. Many of the ecosystems that are most sensitive to damage from acid deposition are located in the northeastern United States and southeastern Canada. Early acid deposition models helped to estabUsh that sulfuric acid and its precursors are transported over long distances, eg, from the Ohio River Valley to New England (86—88). Models have also been used to show that sulfuric acid deposition is nearly linear in response to changing levels of emissions of sulfur dioxide (89). 

TABLE 21.4 Peak Resolution Parameters Valley-to-Peak Ratios, v, and Peak Separation Parameters, P, for Batch 52 Gel... 

Resolution (10% valley definition) Let two peaks of equal height in a mass spectrum at masses m and (m - Am) be separated by a valley that at its lowest point is 10% of the height of the peaks. 

Mixtures for determining resolution Ratio Resolution (M/AM, 10% valley)... 

However, another method used to measure resolution, which is less accurate but less demanding, is to take the peak and valley measurements/and g along the line of zone intersection, shown schematically in Fig. 2.4, so as to calculate P =f/g. Then Equation 2.9 is used to get the resolution... 

FIGURE 2.4 Determining resolution based on a peak-valley measurement for two-dimensional chromatography. The / and g values are measured and used to calculate P =f/g giving the resolution through Equation 2.9. Reprinted with permission from Murphy et al. (1998) by courtesy of the American Chemical Society. 

Figure 2.8 Resolution at 10% valley (a) and at full width at half maximum (FWHM, b)...

Mass Resolution The smallest mass difference Am (Am in Da or Am/m in, e.g., ppm) between two equal magnitude peaks such that the valley between them is a specified fraction of the peak height [3]. 

Two neighboring peaks are assumed to be sufficiently separated when the valley separating their maxima has decreased to 10 % of their intensity. Hence, this is known as 10 % valley definition of resolution, Rio%- The 10 % valley conditions are fulfilled if the peak width at 5 % relative height equals the mass difference of the corresponding ions, because then the 5 % contribution of each peak to the same point of the m/z axis adds up to 10 % (Fig. 3.16). 

Fig. 3.16. Illustration of the 10 % valley and of the Ml width at half maximum (FWHM) definitions of resolution. Peak heights are not to scale.

The % corrected peak area values are shown in Table 2. When an injection time of 20 to 40 sec is used, the assay generated reasonable precision. The overall percent relative standard deviation (%RSD) are 0.7, 1.6, and 7.6 for the HC, LC, and non-main species, respectively. The %RSD of HMW species is relatively high due to poor resolution between the HMW and HC peaks. In this case, we recommend that the HMW species not be integrated separately from the HC component unless there is a clear graphic valley point for integration. 

Mass spectrometry. (+)Fast atom bombardment (FAB) mass spectrometry was carried out with a JEOL JMS-SX/SX102A mass spectrometer. Dried samples were dissolved in methanol-water, mixed with (thio-) glycerol, and applied to a direct insertion probe. During the high resolution FAB-MS measurements, a resolving power of 10,000 (10% valley definition) was used. Cesium iodide, glycerol, or polyethylene oxide (MWav = 600) was used to calibrate the mass spectrometer. 

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