Free column volume

A small column packed with crushed washed tuff was constructed. The column volume was of the order of. 07 ml and assuming about 10% void the free column volume was 0.007 ml. 

Plutonium (237) was deposited on the top of the column. The first 100 ml, or 1.4 x 10 free column volumes, contained about 0.5% of the Pu. About 0.75% of the total was contained 1n 1400 ml or 2 x 105 column volumes (Fig, 21). This implies that the boundary of the water progressed 2 x 105 times more rapidly than the bulk of the plutonium. A typical aquifer will have a rate of water flow between 0.16 to 1.6 km per year. The rate of plutonium... 

Packing type Size (mm) Material Free column volume/ packing volume ) Load HETF (cm / (cm) cm X h) Wol IFp Wnl Flooded (Wd+IFf) ... 

F1 3 —3 mm liquid hold-up at flooding point, based on free column volume... 

Prior to any analytical run, the column must be washed with full strength component B in order to free the column of any impurities remaining from earlier run(s). In general, a 10 minute wash at the flow rates shown in Table 3 will be sufficient. The column is then equilibrated with the starting composition of the solvent to be used for as long as it takes to obtain a steady baseline (2-4 column volumes). The material is injected and the desired gradient is run followed by a wash (2-4 column volumes) at the highest concentration of component B before reequilibration to initial conditions. 

Figure 7.2 Separation of a 10-solute sample with the same liquid system and the same 120 mL CCC column, (a) 108 mL of stationary phase are retained at 1400 rpm and 1 mL/min mobile phase flow rate, (b) Vg = 84 mL at 1100 rpm, 1 mL/min. (c) Vg = 60 mL at 800 rpm, 1 mL/min. (d) Vg = 36 mL at 600 rpm, 1 mL/min. The dotted vertical line corresponds to the column volume and compound 7 with Kq = 1 (Equation 7.2). (Adapted from Berthod, A., Countercurrent Chromatography The Support-Free Liquid Stationary Phase, Elsevier, Amsterdam, 2002.)...

Here, Ve(P) = qvte(P) is the elution volume of the P-mer measured at the end z = L of the column with a free cross-section q, at the elution time te(P), and = qL is the void column volume as defined above the volume ratio rv in the transport zone is assumed to be equal to the overall value, Eq. (2 b). Introducing the correct partition function... 

The experimental measurement of some of the operational parameters for the PFIER was carried out with the help of SPECTRUM disposable, cylindrical polystyrene minicolumns with an internal diameter (d) of 0.732 0.001 cm, which implies a cross sectional area (S) of 0.421 0.002 cm2, and a total length of 7 cm [38,53], The columns were prepared with a bed length (D) of 4.20 0.02 cm filled with crushed and sieved Na-SW zeolite. The free bed volume was Vb 0.8 0.1cm3. In the experimental PFIER, volumetric flows of dilute aqueous solutions of Pb(N03)2, Cu(N03)2, Co(N03)2, and Ni(N03)2 with initial concentrations that are reported below were passed [38,53], The used salts were pure per the analysis products provided by Fisher. 

A simple but realistic model of the above process is readily constructed. Let us imagine a uniform adsorbent bed of length L, with total weight of adsorbent W, and free volume K (for a column filled with adsorbent, K is the volume of the column minus that of the adsorbent, i.e., the column volume accessible to solvent). A small quantity of a compound X (sample) is added to one end of the bed, the solvent is washed through the bed, and the process is stopped when the solvent front reaches the other end of the bed. At equilibrium the relative extent of adsorption of X is given by... 

As far as the technical aspects are concerned, the lEC is easier than the SEC. The lEC does not require perfectly poured columns, and the sample volume can amount to a multiple of the column volume. In addition, the lEC exhibits better purification factors than the SEC (between 3 and 15, depending on protein and conditions) and concentrates the sample. The yield is also often better (between 50 and 80%). With multistep purifications, it is a good idea to have the lEC at the beginning. Afterward, you have the sample in a small volume, free of endogenous ligands or other disruptive extract components. 

In frontal chromatography, the MIP to be tested is used as the stationary phase usually in a HPLC column. The MIP column is first equilibrated with pure solvent and then switched over to a solution containing a constant concentration of analyte, which is taken as the free concentration (F). The corresponding bound concentration (B) is calculated from Eq. (1) in which V is the volume of solution it takes for the column to re-establish equilibrium, Vo is the column volume and m is the mass of polymer in the column... 

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