Elution experiments

Fissure Elution Experiments. The migration characteristics of americium by water transport in fissures fabricated from gray hornblende schist were determined. Fissures not used in the previous sorption experiments were used for these elution experiments. A diagram of the experimental apparatus is shown in Figure 4. Solution reservoirs were attached above the fissures and the small bore tubes affixed to the bottom of the fissures were connected to solution metering pumps. 

Before the elution experiments were performed, the "schist"-equilibrated water was pumped through the fissures for two days to allow the fissure walls to interact with the rock-equilibrated water. 

Figure 4. Diagram of apparatus used for fissure elution experiments...

The second set of fissure-elution experiments was performed in the same manner as described for the first set of fissure-elution experiments. The difference in the second set of experiments was that after 0.67 fissure volumes of stock solution were drawn into the fissures at their respective flow rates, the stock solution in the reservoirs was replaced with rock-equilibrated water. The solution metering pumps were not turned off during the exchange. Subsequently, a total of twenty fissure volumes of solution was drawn through each fissure before the metering pumps were turned off. After the metering pumps were stopped, the rock-equilibrated water was removed from the reservoirs and the solution in the fissures was rapidly drawn off. 

The approach of Jandera and Chura ek allows the optimization of the resolution of one given (arbitrary) pair of sample components and the minimization of the retention volume of another (arbitrary) solute. It requires knowledge of the isocratic retention vs. composition relationships of these three solutes. The information needed may be acquired from gradient elution experiments performed as part of the optimization procedure, or from separate isocratic experiments. The selection of the three arbitrary solutes considered during the optimization process appears to have a large effect on the result and the resolution cannot be optimized throughout the chromatogram. 

Cj(cp) can be obtained e3q)erimentally from isocratic elution experiments at different Cp values, or from linear gradient elution experiments where the ratio G = pL/v is varied. In the latter case, the retention factor is obtained by differentiation of Eq. (16-190) from... 

Because of the very high polarity of water, even trace amounts of moisture in the mobile phase can affect significantly the retention of sample compounds in NPC. Hence, it is very important to control the water content in the chromatographic system. As the water content usually differs in various organic. solvents u.sed as the components of the gradient, the easiest way to control this is to use carefully dried solvents. Finally, it is very important to control the temperature of the column to get reproducible results in repeated gradient-elution experiments, especially in NPC. 

Before starting extensive experiments, a procedure recommended by Kaiser and Oel-rich (1981) to rule out adsorbents by fast experiments should be employed. Each elution experiment takes about 20 s. For this purpose samples are applied on a 50 X 50 mm TLC plate at 9 points, which are exactly 10 mm apart. Five microlitres of methanol are drawn into a micro-capillary with a Pt-Ir point. By applying the point of the filled capillary on one of the sample points on the plate, methanol is introduced onto the plate. A miniature radial chromatogram of ca. 7 mm diameter is produced. If the sample components remain at the point of application, the use of this adsorbent type is ruled out for HPLC usage. To make sure, the procedure is repeated with 5 pi of acetonitrile and tetrahydrofuran, respectively. If the products still remain at the point of application, the situation will not be changed by using any other mobile phase that is suitable for preparative chromatography work. 

A plexiglass column, which was used to prevent calcium contaminations, was filled up to 80 cm with 15 g of the exchanger (columri diameter =1.2 cm). The distribution coefficient of calcium between this exchanger and a mixture of 90% CH3OH/10% H2O (v/v) was analyzed to be 4 ml/g which was sufficiently high for an elution experiment. The half-life of the calcium ion exchange reaction with this resin is about 20 s which means that not too high elution speeds must be applied (about 20 ml/h). Different fractions of the calcium elution were analyzed for their Ca/ Ca... 

Elution Experiments. In addition to reversible adsorption, inactivation or degradation of viruses by various types of surfaces such as metal oxides (27), aluminum metal (28), magnetite (29), clays (30) and soils (31) have been reported. The mechanisms were identified to be either degradation of the capsid and/or the nucleic acid. However, such inactivation may be only specific to certain t)rpes of viruses. 

Resin Effects on Gas Elution. Elution experiments were also performed on PF-bonded particleboard and on Southern pine chips (furnish without resin) that had sorbed formaldehyde via room temperature vapor phase equilibration (see Appendix Id and 2). Points to be noted here are as follows ... 

Examples Include binary, ternary, quaternary, linear and multiple-linear solvent gradients as well as for cases Involving stationary phase programming (coupled column gradient elution experiments). 

Fig. 4. Plots of log Ic versus based on gradient experiments for /3-endorphin-related peptides 7, 8, 10, 11,14-15. The plots were derived from best-fit analysis to the data points obtained from gradient elution experiments, where tQ = 20, 30, 40, 60 and 120 min and / = ml/min. Column, developmental octadecylsilica, dp= 6/im, Pd = 13 nm, 25 cm x 4.6 mm ID. Solvent A, 0.1 % trifluoroacetic add (TFA) in water solvent B, 0.1% TFA in water-acetonitrile (50 50). See Table 2 for the code to polypeptide structure and for the calculated slope parameter S and log k values. Note the changes in band spacing for peptides 7, 8, 10 and 11 which illustrate the potential for selectivity manipulation through changes in the gradient steepness parameter, b. From [4].

Eor elution experiments (Figure 1) Glueckauf showed (1958) that e is obtained from the enrichment, if the number of equivalent theoretical plates N is large and known ... 

With the cation exchanger 10" a= — 7 could be achieved in elution experiments, with the anion exchanger 10" 8 = 7 in band displacement experiments. More recently this technique was employed for the separation of and from with 10 8/Am of 4. See Table 2 for further information. 

Figure 5 An example of a zonal elution experiment, in which small injections of L-tryptophan are made on to an immobilized human serum albumin column in the presence of increasing amounts of phenytoin in the mobile phase.

---