Temperatures retention, effect

First Carbonation. The process stream OH is raised to 3.0 with carbon dioxide. Juice is recycled either internally or in a separate vessel to provide seed for calcium carbonate growth. Retention time is 15—20 min at 80—85°C. OH of the juice purification process streams is more descriptive than pH for two reasons first, all of the important solution chemistry depends on reactions of the hydroxyl ion rather than of the hydrogen ion and second, the nature of the C0 2 U20-Ca " equiUbria results in a OH which is independent of the temperature of the solution. AH of the temperature effects on the dissociation constant of water are reflected by the pH. 

Lochmiiller, C. H., Moebus, M. A., Liu, Q., and Jiang, C., Temperature effect on retention and separation of poly(ethylene glycoljs in reversed-phase liquid chromatography, /. Chromatogr. Sci., 34, 69, 1996. 

Hutchins DA, Stupakoff I, Fisher NS. 1996a. Temperature effects on accumulation and retention of radionuclides in the sea star, Asterias forbesi Implications for contaminated northern waters. Mar Biol 125 701-706. 

Hutchins DA, Teyssie J-L, Boisson F, et al. 1996b. Temperature effects on uptake and retention of contaminant radionuclides and trace metals by the brittle star Ophiothrix fragilis. Mar Environ Res 41(4) 363-378. 

Obviously, the magnitude of the temperature effect on retention depends on the difference in the enthalpy of the solute in either phase, and is specific for each solute. Therefore, it also changes the column selectivity. There is no retention and no temperature effect for AH=0. 

This temperature effect is the usual one for a regular or enthalpy-entropy compensated chromatographic separation, suggesting that the retention of each... 

The impact of the eluent temperature is shown in Figure 12.20. Increasing temperature tends to increase retention. This effect is usually not observed in liquid chromatography, in accordance with the thermodynamics of the retention phenomenon described by the Gibbs equation. However, temperature has an... 

Rf passes through the quartz column at a lower retention temperature compared to Hf. This observation received considerable attention and was interpreted as evidence for relativistic effects, since the higher volatility of RfCl4 compared to that of HfCl4 is unexpected on the basis of classical extrapolations. 

As is evident from the preceding discussion, the retention behavior of a polypeptide or protein P- expressed in terms of the capacity factor k is governed by thermodynamic considerations. Peak dispersion, on the other hand, arises from time-dependent kinetic phenomena, which are most conveniently expressed in terms of the reduced plate height he, . When no secondary effects, i.e., when no temperature effects, conformational changes, slow chemical equilibrium, pH effects, etc. occur as part of the chromatographic distribution process, then the resolution Rs, that can be achieved between adjacent components separated under these equilibrium or nearequilibrium conditions can be expressed as... 

Litzen and Wahlund systematically studied error sources like temperature effects, sample overloading, sample adsorption to the accumulation wall membrane and influences of the carrier liquid composition, that occur with Fl-FFF [455] the latter has already been discussed above. It was shown that preservation of constant channel temperature is very important as repeated measurements of an identical sample resulted in gradually decreasing retention times due to increasing channel temperature caused by frictional heat, especially when using high flow rates. As constant channel temparature is usually not fulfilled with the standard Fl-FFF channels, which simply operate at room temperature without any temperature control, this is an important point to consider. 

The next variable investigated was the effect of temperature on the analyte retention. The effect of temperature on the retention and selectivity of the para and ortho isomers at wpHs 2, 8, and 8.6 was studied (figures 8-31, 8-32, and 8-33). The effect of temperature could be used to optimize the run time and the apparent efficiency of the separation. At a buffer pH of w2.0, the effect... 

In "Figure 10" the inversion is observed based on columns with different film thickness. These examples demonstrate that in many cases a better chromatographic separation is obtained taking advantage of favorable temperature effects. These are best explained by a consideration of retention indices. 

The test cycle and activity measurements were as shown in Fig. 1. It included a high temperature mode (1000 deg C) for 25% of the cycle time to take account of autobahn driving. The test procedure was developed to simulate the conditions found on the AMA City Driving Cycle, with modification for Europe, and has a nominal space velocity of 40000/hr which duplicates 48km/h steady state vehicle operation. To be able to evaluate temperature effects on Pb retention another catalyst was aged on a modified cycle that used only 730 deg C for 6% of the cycle instead of 1000 deg C for 25% of the cycle. 

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