Intensity different concentrations

Separations similar to those obtained with dry induced-roll devices can be obtained with cross-belt separators (Fig. 19-42). These units are built with up to eight poles, each of which can operate at different magnetic-field intensities to allow simultaneous production of different concentrates. However, capacity is low, and installed costs per ton capacity are high compared with induced-roll units. 

Fig. 43.—Diagrammatic Plots of Reaction Time, High-intensity Plateau, and Overall Persistence-time at Different Concentrations of Sucrose. ...

Thus, the increase in concentration needed to match the effect of a 10-fold increase in sucrose concentration is 0.154/2.44 x 10 = 630-fold. Crosby and coworkers suggested that this is close to the situation that occurs with saccharin, and it is doubtless responsible for the differences in perceived sweetness intensity (200-700 times that of sucrose) for sensory determinations conducted at different concentrations. 

Fig. 29. Decrease in intensity of nitroxide ESR signal npon addition of deuterated ethanolamine to ethanolamine ammonia lyase containing spin labeled cobinamide coenzyme. The two curves are for different concentrations of coenzyme to enzyme. The arrows indicate the point at which alcohol dehydrogenase and NADH was added to remove acetaldehyde from the enzyme. Note that full intensity is regained...

Khashaba et al. [34] suggested the use of sample spectrophotometric and spectrofluorimetric methods for the determination of miconazole and other antifungal drugs in different pharmaceutical formulations. The spectrophotometric method depend on the interaction between imidazole antifungal drugs as -electron donor with the pi-acceptor 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, in methanol or with p-chloranilic acid in acetonitrile. The produced chromogens obey Beer s law at Amax 460 and 520 nm in the concentration range 22.5-200 and 7.9-280 pg/mL for 2,3-dichloro-5,6-dicyano-l,4-benzoquinone and p-chloranilic acid, respectively. Spectrofluorimetric method is based on the measurement of the native fluorescence of ketoconazole at 375 nm with excitation at 288 nm and/or fluorescence intensity versus concentration is linear for ketoconazole at 49.7-800 ng/mL. The methods... 

Fig. 28 Top Effect of dilution on Rh and Kc/lg o of the mesoglobules ( ) formed upon heating of 0.2 gL1 aqueous solution of PVCL-g-18. Bottom Scattering intensity at 90° from polymer solution of different concentration. (Reprinted with permission from Ref. [180] copyright 2005 Elsevier)... 

A later paper65 reported a fluorescence maximum for leucovorin at 365 nm when excited at 314 nm in a pH 7 solution the concentration was 5 x 10-5 M. Variation between these data and other values was attributed to sample impurity, pH of solution, and quenching. The authors made an attempt to correlate structure and fluorescence of reduced folates. Similarity between tested compounds and jj-aminobenzoyl-glutamate lead them to conclude that this portion of the molecule is responsible for maxima at 360-425 nm when excited at 300-320 nm. They suggested that intensity differences may arise from various substitutions on the tetra-hydropteridine moiety. 

Fig. 15.16 The change in the TEo solvent blue CLW mode intensity and the calibration curve for different concentrations of paraoxon. Error bars represent 1 standard deviation, n 4. Reprinted from Ref. 53 with permission. 2008 The Royal Society of Chemistry...

Imagine we need to investigate further the intensity of the stain. We would start by making several curries, each made in an identical pan and cooked for an identical length of time, although each containing a different concentration of red capsaicin. We expect the molecules of capsaicin to occupy a larger proportion of possible adsorption sites when there is more of it in solution and we expect 9 to be smaller when there is less capsaicin in solution. This is indeed found to be the case. 

Almost all methods of chemical analysis require a series of calibration standards containing different amounts of the analyte in order to convert instrument readings of, for example, optical density or emission intensity into absolute concentrations. These can be as simple as a series of solutions containing a single element at different concentrations, but, more usually, will be a set of multicomponent solutions or solids containing the elements to be measured at known concentrations. It is important to appreciate that the term standard is used for a number of materials fulfilling very different purposes, as explained below. 

In addition to the emission due to the test element, radiation is also emitted by the flame itself. This background emission, together with turbulence in the flame, results in fluctuations of the signal and prevents the use of very sensitive detectors. The problem may be appreciably reduced by the introduction into the sample of a constant amount of a reference element and the use of a dual-channel flame photometer, which is capable of recording both the test and reference readings simultaneously. The ratio of the intensity of emission of the test element to that of the reference element should be unaffected by flame fluctuations and a calibration line using this ratio for different concentrations of the test element is the basis of the quantitative method. Lithium salts are frequently used as the reference element in the analysis of biological samples. 

In the determination of M , the intensity of scattered light is measured at different concentrations and at different angles 6). The incident light sends out a scattering envelope that has four equal quadrants (Figure 3.11a) for small particles. The ratio of scattering at 45° compared with that at 135° is called the dissymmetry factor or dissymmetry ratio Z. The reduced dissymmetry factor Z is the intercept of the plot of Z as a function of concentration extrapolated to zero concentration. 

In this technique, one measures i/I0 at 6 = 45° and 0 = 135° for dispersions at several different concentrations. It should be noted that the factor (1 + cos2 0) in Equation (24) has the same value for these two angles of observation. Therefore any deviation of the ratio of the intensities z from unity must measure the ratio of the P(6) values at these two angles [See Equation (47)] ... 

As with any spectrophotometer instrument, the light intensity is determined at each wavelength using a photomultiplier tube. Emission measurements can be made over a wide dynamic range, which is an interesting feature because elements with widely different concentrations or sensitivity can be measured in a single sample solution. 

The rate of formation of oxidation intermediates was followed by withdrawing aliquots during oxidation runs and determining intensities of the parent peaks in low voltage mass spectra as measures of the relative concentrations of starting hydrocarbon and products. Although sensitivity—i.e., the proportionality factor between parent-peak intensity and concentration—differs from one compound to another, peak heights for any one compound in the spectra of samples of equal size (0.6ft) are... 

Owing to the very high rate of decomposition, in-situ measurement of concentration by means of Raman spectroscopy was applied. The peroxide used was f-butylperoxy pivalate (see Chapter 5.1, Table 5.1-2) dissolved in n-heptane at a concentration of 1 wt.%. In order to observe the change in intensity of absorption of the 0-0 bond at 861 cm 1, the spectrometer was adjusted to this wave number. The change of intensity is an indication of the reduction in the peroxide concentration, and was recorded as a function of time. The apparatus was calibrated before measuring the intensity of peroxide solutions of different concentrations [22],... 

Fig-1. Rate of formation of polybutene sulfone from monomer mixtures containing 9,1 mole-% 1-butene. (A) and (B) photochemical initiation at two different intensities (G) and (H) initiation by silver nitrate at two different concentrations (/) initiation by benzoyl peroxide. Reproduced, with permission, from Dainton and Ivin Disc. Faraday Soc. 14, 199 (1953). 

Fig. 3.12 Intensity contribution function, extracted from dynamic light scattering intensities, versus apparent hydrodynamic radius for PBO PEO PBOiz in aqueous solution at 10 °C and different concentrations (indicated) (Zhou el al. 1996c),...

---