Extraction calculation procedures

Table 1 Representative data evaluating data obtained from various studies for calculating the LOD and LOQ values for the extraction/analysis procedure using the 3(RMSE)/slope method to estimate the LOD/LOQ and the 799, j,seloq method to calculate the MDL and MQL...

If necessary, the implicit nature of the calculation may, however, be avoided by a reformulation of the holdup relationship into an explicit form. The resulting calculation procedure then becomes much more straightforward and the variation of holdup in the column may be combined into a fuller extraction column model in which the inclusion of the hydrodynamics now provides additional flexibility. The above modelling approach to the column hydrodynamics, using an explicit form of holdup relationship, is illustrated by the simulation example HOLDUP. 

For example, if the internal standard is much more volatile than the analyte it is likely that more will be lost during storage, if it is much more polar it may be extracted either much more or less efficiently than the analyte during sample work-up, or if the internal standard is different chemically then derivatization procedures may be more or less efficient (it may be argued that as long as this differential behaviour is reproducible, it can be allowed for in the calculation procedures but significant extra work would be required to confirm such reproducibility). 

The iterative calculation procedure is outlined in Figure 14.10. The method is an adaptation to extraction by Tsuboka and Katayama (1976) of the distillation calculation procedure of Wang and Henke [Hydrocarb. Proc. 45(8), 155-163 (1967)]. It is also presented by Henley and Seader (1981, pp. 586-594). 

The proposed calculations procedure allows one to approximate the experimental extraction curve and to determine the diffusion constant and activation energy for each peak of the curve. 

Related Calculations. This basic calculation procedure can be extended to the case of countercurrent multistage extraction with reflux. A schematic of the basic extractor is shown in Fig. 9.5. For this extractor there are N stages in the extracting section, 1E to NE, and there are M stages in the stripping section, 15 to MS. 

In the same article Treybal utilizes information on mass transfer from solids and heat transfer to spheres, to arrive at a procedure for making rough estimates of extraction stage efficiencies for baffled vessels agitated with flat-blade turbine impellers. Results from this calculation procedure are in general agreement with the experimental results of Flynn and Treybal and of Overcashier et al. 

Two typical sets of potentiometric titration data are presented in Table I, while the data for solvent extraction measurements are given in Table II. Again, an iterative calculation procedure was used to obtain... 

Bruce S. Hoiden, M.S. Process Research Leader, The Dow Chemical Company Member, American Institute of Chemical Engineers [Process Fundamentals and Basic Calculation Methods, Calculation Procedures, Computer-Aided Calculations (Simulations), Single-Solvent Fractional Extraction with Extract Reflux, Liquid-Liquid Phase Separation Equipment]... 

The desired concentration of extract is set equal to, and the raffinate in equilibrium with the first stage, Xy, is determined from the equilibrium curve. With this value ofX, is calculated from the above operating equation then X2 is determined from the equilibrium line and the calculation procedure is continued until X X. ... 

In the present example, nitric acid is an extractable component, whose split between extract and raffinate streams cannot be specified in advance. However, in the calculational procedure to be described, it is necessary to start with specified concentrations of all... 

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