Intensity ratio method

In addition to the techniques outlined above, many other methods have been developed for droplet sizing. These include, for example, intensity ratio method, phase optical-microwave method, and dual-cylindrical wave laser technique)1(n etc. 

The intensity ratio method is based on measurements of light scattered at two angles and applies to the size range 0.1 to 10 pm [187]. Due to the possibility of large errors [188] the method has found little application. 

The ratio of the polarized light intensity scattered from two different coaxial beams illuminating a particle can be used to determine particle size. Azzizy and Hess [191] used two coaxial beams of different wavelengths at 30° from the forward axis polarized in different directions. The ratio of these two parameters gives a unique curve that is a function only of particle size. They found errors of a similar magnitude to those found with intensity ratio methods. 

The reference intensity ratio method is based on the experimentally established intensity ratio between the strongest Bragg peaks in the examined phase and in a standard reference material. The most typical reference material is corundum, and the corresponding peak is (113). The reference intensity ratio k) is quoted for a 50 50 (wt. %) mixture of the material with corundum, and it is known as the corundum number . The latter is commonly accepted and listed for many compounds in the ICDD s Powder Diffraction File. Even though this method is simple and relatively quick, careful account and/or experimental minimization of preferred orientation effects are necessary to obtain reliable quantitative results. 

In the present study, a FLIM measurement system was constructed and applied to Halobacterium salinarum (Hb. salinarum) loaded with 2, 7 -bis-(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) to obtain information on the intracellular environment as well as the intracellular pH in each ofthe cells [9-12]. Hb. salinarum belongs to the family of extreme halophilic archaebacteria, and considerable attention has been paid to this bacterium in relation to proton transport, phototaxis or the adaptation of an organism to extreme environments [13-15]. Intracellular pH is an essential parameter for Hb. salinarum in the regulation of intracellular processes [14, 16, 17], and fluorescence intensity ratio methods have been used to measure the intracellular pH [18,19]. The... 

As shown in the next section, the intracellular pH can be evaluated from the fluorescence lifetime of BCECF inside cells without any ratio methods [10]. The relation between the intracellular pH and the lifetime of BCECF in Hb. salinarum indicates that the lifetime decreases with decreasing intracellular pH. Based on the correlation function between the intracellular pH and the fluorescence lifetime, the average value of the intracellular pH of Hb. salinarum was estimated to be 7.1, which is roughly the same as that obtained with the intensity ratio method [18]. 

A Philips PW-14(X) wavelength dispersive spectrometer equipped with four crystals (LiF, Ge, PET, and TIAP) was used for the analysis. The rhodium target tube was operated at 2.5 kW (50 kV and 50 mA). The sample holders were 32 mm in diameter with a copper mask. The elements determined and their respective peak and background times are shown in Table 2. The intensity ratio method was employed using a synthetic monitor specimen. 

The evaluation of mixing properties of melts and solid solutions from measured ion intensities and temperatures are described in the reviews by Chatillon et al. [12], Sidorov and Korobov [115], as well as Raychaudhuri and Stafford [13] and the references quoted in these articles. The chemical activities, or activity coefficients, can be obtained from the partial pressures of the mixture components. The pressure calibration constant (see Sect. 2.4) has to be determined in this case. The pressure calibration can be avoided by the use of the ion intensity ratio method described by Lyubimov et al. [116]j Belton and Fruehan [117], as well as Neckel and Wagner [118, 119]. The Gibbs-Duhem relation is used to obtain the activity coefficient f of the component A in the mixture... 

Chemical activities are obtained by a similar equation. The ion intensity ratio method has been used successfully for the study of numerous systems (see e.g. Sect. 3.4). However, no consistency check of the activities by the Gibbs-Duhem relation is possible since this relation has to be used to obtain the equations necessary for the evaluation according to the ion intensity ratio method. 

Only solid solutions were present under the conditions of the investigation of the Fe-Co [242], Ni-Cu [250], and SnTe-PbSe [262] systems given in Table 7. The thermodynamic activities, excess Gibbs energies, mixing enthalpies and excess entropies were determined by the use of the ion intensity ratio method for the Fe-Co and Ni-Cu systems as described for the melts. The partial pressure of the molecules SnTe, SnSe, PbTe, and PbSe were obtained for different compositions of the quasi-binary system SnTe-PbSe using the isothermal evaporation technique. 

Fig. 2. Thermodynamic activities ofTi and A1 at 1473 K in solid Ti/Al alloys of different compositions obtained by the ion intensity ratio method ( ) and by the equation a = p, / p ( , )...

Quantification of the relative abundance of crystalline phases in a multiphase mixture is an everyday problem in a wide range of applications. Common examples are evaluation of the yield in inorganic synthesis and catalytic processes, characterization of raw mineral materials for industrial processes, quality check of fired ceramic products, and many more. While in most cases the required accuracy level of the analysis is a few percent at best, in particular cases such as in the quantification of phase contaminants in technologically important materials, or of hazardous and toxic phases in environmentally dispersed aerosols, the required level of accuracy must be substantially lower than 1 wt% relative abundance. Accuracy levels of 2-3 wt% are commonly reached if standard procedures of quantitative phase analysis by diffraction data are properly performed. Generally employed analytical methods include the internal or external standard method, the matrix flushing method, and the reference intensity ratio method. Very recently, the availability of analysis techniques of powder diffraction data based on full-profile (Rietveld method), originally developed... 

An alternative approach to the quantitative analysis formalism is the ratio method. Here we consider the ratio of the intensities of any two edges A and B. Using Equation (3) we can show that... 

The modification improves performance and is interesting in connection with x-ray emission spectrography (Chapters 7, 8, and 9). It consists in measuring the intensity of tin Ka relative to that of scattered x-rays entering the detector from an analyzing crystal set for the reflection of x-rays 2.2 A in wavelength. As the tin coating becomes thicker, increased attenuation of the x-rays scattered by the iron cause s the intensity ratio to increase more rapidly than does the intensity of tin Ka. Table 6-3 contains performance data for the Quantrol on Method II (modified). The instrument can also be set up to use industrially a modification of Method III. 

No calibration was required and the percentage of only one element needed to be established, for the alloy was binary. The atomic numbers of copper and zinc being adjacent, the intensity ratio of their K lines could, after an appropriate adjustment of experimental conditions, be assumed equal to the ratio of the number of atoms present of each metal. Under these simple conditions, compositions could be calculated satisfactorily from intensity ratios, as is shown by the following results for a series of 16 x-ray determinations on such an alloy found by chemical methods (details not given) to contain 73.00% copper average copper content, 73.16% standard deviation for a single determination, 0.27%... 

In the language of this book, the procedure summarized by Equation 11-2 may be described as follows (1) The analysis is made by the comparative method, unknown and standard being compared as in Section 7.8. (2) By the use of intensity ratios, the comparison is... 

For ail samples, both a.p. and s.o., irrespective of the preparation method, the experimental intensity ratios, V2p/Zr3d, increased proportionally to the V-content up to 3 atoms nm 2 (pjg 2). The ratio approaches those calculated with the spherical model proposed recently by Cimino et al. [27] (full line in Fig. 2). For ZV samples with V-content < 3 atoms nm 2, this finding shows that vanadium species are uniformly spread on the Zr02 surface. On ZV catalysts with a larger V content (not shown in Fig. 2), the intensity ratios were markedly larger than the corresponding values yielded by the spherical model. The results obtained on samples with V-content > 3 atoms nm 2 point therefore to a V surface enrichment. 

As the majority of stabilisers has the structure of aromatics, which are UV-active and show a distinct UV spectrum, UV spectrophotometry is a very efficient analytical method for qualitative and quantitative analysis of stabilisers and similar substances in polymers. For UV absorbers, UV detection (before and after chromatographic separation) is an appropriate analytical tool. Haslam et al. [30] have used UV spectroscopy for the quantitative determination of UVAs (methyl salicylate, phenyl salicylate, DHB, stilbene and resorcinol monobenzoate) and plasticisers (DBP) in PMMA and methyl methacrylate-ethyl acrylate copolymers. From the intensity ratio... 

Whereas the use of conventional fast atom bombardment (FAB) in the analysis of polymer/additive extracts has been reported (see Section 6.2.4), the need for a glycerol (or other polar) matrix might render FAB-MS analysis of a dissolved polymer/additive system rather unattractive (high chemical background, high level of matrix-, solvent- and polymer-related ions, complicated spectra). Yet, in selected cases the method has proved quite successful. Lay and Miller [53] have developed an alternative method to the use of sample extraction, cleanup, followed by GC in the quantitative analysis of PVC/DEHP with plasticiser levels as typically found in consumer products (ca. 30 %). The method relied on addition of the internal standard didecylphthalate (DDP) to a THF solution of the PVC sample with FAB-MS quantitation based on the relative signal levels of the [MH]+ ions of DEHP and DDP obtained from full-scan spectra, and on the use of a calibration curve (intensity ratio m/z 391/447 vs. mg DEHP/mg DDP). No FAB-matrix was added. No ions associated with the bulk of the PVC polymer were observed. It was... 

Using zinc oxide as the internal standard, the relative amounts of two polymorphic forms of fenretinide were quantified [55], Mixtures containing 25, 50, and 75% w/w form I were prepared by mixing authentic standards of form I and form II fenretinide. After the addition of the internal standard, the maximum intensities (peak heights) of the 4.6 A line (peak at 19.1° 20) of fenretinide form I (/19. i) and the 2.8 Aline (peak at 31.8° 20) of zinc oxide (/318) were determined. A plot of the intensity ratio (/19.//31.8) as a function of the weight percent form I was linear. The method was reported to be precise and accurate to within 6%. 

Heavy residual fuel oils and asphalts are not amenable to gas chromatography and give similar infrared spectra. However, a differentiation can be made by comparing certain absorption intensities [52], Samples were extracted with chloroform, filtered, dried, and the solvent evaporated off at 100 °C for a few minutes using an infrared lamp. A rock salt smear was prepared from the residue in a little chloroform, and the final traces of solvent removed using the infrared lamp. The method, which in effect compares the paraffinic and aromatic nature of the sample, involves calculation of the following absorption intensity ratios ... 

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