Linear mass experiments, procedure

The competitive adsorption isotherms were determined experimentally for the separation of chiral epoxide enantiomers at 25 °C by the adsorption-desorption method [37]. A mass balance allows the knowledge of the concentration of each component retained in the particle, q, in equilibrium with the feed concentration, < In fact includes both the adsorbed phase concentration and the concentration in the fluid inside pores. This overall retained concentration is used to be consistent with the models presented for the SMB simulations based on homogeneous particles. The bed porosity was taken as = 0.4 since the total porosity was measured as Ej = 0.67 and the particle porosity of microcrystalline cellulose triacetate is p = 0.45 [38]. This procedure provides one point of the adsorption isotherm for each component (Cp q. The determination of the complete isotherm will require a set of experiments using different feed concentrations. To support the measured isotherms, a dynamic method of frontal chromatography is implemented based on the analysis of the response curves to a step change in feed concentration (adsorption) followed by the desorption of the column with pure eluent. It is well known that often the selectivity factor decreases with the increase of the concentration of chiral species and therefore the linear -i- Langmuir competitive isotherm was used ... 

The final determination of the CBs was performed by capillary gas chromatography using either mass selective detection or electron capture detection. Each participant had validated its method by performing experiments on recovery, extraction efficiency, procedure blanks and detector linearity. 

The final determination of the CBs was performed by capillary gas chromatography with electron capture detection mass spectrometry was used as complementary technique to confirm the identity of each of the CBs determined. Each participant had validated its method by performing experiments on recovery, extraction efficiency, procedure blanks and detector linearity. The seven individual CB calibrants were supplied to the participants as pure, crystalline CRMs from BCR (CRMs Nos. 291,293, 294,295, 296. 297 and 298). Each laboratory was requested to prepare separate calibration solutions of the appropriate concentration, in iso-octane, to calibrate the detector and lying within its linear range. The use of at least one internal standard was mandatory the participants, however, were left free to select the internal standard(s) best suited to their methods. They had to verify that the selected compounds did not occur in the candidate reference material or did not interfere with compounds present in the material. A series of pure dichlorobenzylalkyl ethers (DCBEs) was made available to the participants but other internal standards were also accepted of which the list is given in the certification report [21] along with additional details on calibration procedures. 

In this experience, the colloid suspension was introduced into a reactor of volume equal to 50 mL and stirred to ensure homogeneity. At time zero, the polymer solution was injected at constant rate and periodically the corresponding volume of the suspension was collected for a certain time to determine the aggregate mass characteristics and to start fragmentation experiments by immersion of these aggregate samples in the polymer solution of concentration C /30. This procedure allows the surface coverage T(f) to be a linear function of the injection time t due to fast total adsorption of the injected polymer. The variations with time of the average masses N(t) and... 

The validity of the models described can be tested by comparing experimentally measured reduced mobilities of several ions in the linear IMS with the predicted coefficients calculated according to the three models. The main features of interest were the correlations of mass with mobility and temperature with mobility another interesting feature is the effect of the drift gas on mobility coefficients (the last two are discussed in Chapter 11). Six parameters are needed in the modeling a, r, z, polarizability, reduced mass, and temperature. The last three arise from direct physical measurements, while the other parameters (fl, r, z) are optimized by a fitting procedure to minimize the deviation between calculated and measured mobility constants. The values of T and were calculated from a, r, and z, and the dimensionless collision cross section (1 was taken from Table 1 in Reference 9. In practice, a discrete value of a was chosen, and initial values for and z were estimated. The parameters Tq and z were then optimized to obtain a good fit with experimental data points by minimizing the squared sum of deviations between theory and experiment. Special attention... 

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