Liquid chromatography experiment

In any liquid chromatography experiment, the composition of the mobile phase is very important in the total separation scheme. In Chapter 11, we discussed the role of a liquid mobile phase in terms of the solubility of the mixture components in both phases. Rapidly eluting components are highly soluble... 

A series of derivatives of tetramic acid were synthesized and complexed to cop-per(II) (Cu-TA,Fig.21) [176,177]. At 300 MHz,the Rt value of Cu-aTA is 0.073 0.004 mM 1 s-1 and the R2 value is 0.091 0.006 mM 1 s 1 [176]. The ability of the Cu-TA derivatives to cross membranes was measured using defolliculated Xeno-pus laevis oocytes as model cells. Using MR microscopy techniques, Cu-aTA, Cu-bTA, Cu-cTA and Cu-eTA were all found to cross into the cytoplasm of the cells [177]. Additionally, atomic absorption spectroscopy revealed the presence of Cu-dTA and Cu-fTA, suggesting that while the complexes failed to cross the cell membrane that they were stored in the membrane-bilayer. Liquid chromatography experiments demonstrated that Cu-aTA crosses membranes intact [176]. 

Both Equations 5.1 and 5.2 can be solved with appropriate boundary conditions and interfacial interaction force constants, generated from liquid chromatography experiments. 

Solid-phase extraction (SPE) (Fig. 6) is a miniature version of the liquid chromatography experiment. It was commercialized and introduced in the late 1970s. With the availability of prepacked cartridges, SPE first became popular in the mid-1980s [19]. It has been widely applied to sample cleanup in the drug discovery... 

On the basis of analysis of retention time data obtained from liquid chromatography experiments reported earlier ( ) the existence of interfacial water is assumed at the solution polymer Interface and the equilibrium concentration of solute between stationary- and mobile-phases is regarded as that between... 

We wish to thank A. Revillon for the liquid chromatography experiments. 

C. D. Wick, J. I. Siepmann, W. L. Klotz and M. R. Schure, Temperature effects on the retention of -alkanes and arenas in helium-squalane gas-liquid chromatography experiment and molecular simulation, /. Chromatogr., A, 2002, 954, 181-190. 

In a high-performance liquid chromatography experiment, the dependence of the retention parameter, k, on three factors was investigated. The factors were pH (factor P), the concentration of a counter-ion (factor T) and the concentration of the organic solvent in the mobile phase (factor C). Two levels were used for each factor and two replicate measurements made for each combination. The measurements were randomized. The table below gives the average value for each pair of replicates. 

Compounds 23a-23d were tested as tryptophan carriers across bulk model membranes. Transport was conducted with a U-tube that contained a dichloromethane phase between two water phases. At 1 mM concentration, 23a transported 12% of available Trp with only 20% enantioselectivity after 2 h. Increasing transport times led to even less enantioselection. Compounds 23b-23d behave similarly in Trp transport under these conditions. However, reducing the concentration of 23a to 125 XM resulted in greatly enhanced enantioselection (73% ee), though with a reduced rate of transport. These results suggest that 23a can select for the matched L-isomer of tryptophan, but competition with the D-isomer occurs when the concentration of L-Trp becomes depleted. Indeed, HPLC (high-performance liquid chromatography) experiments revealed that near the membrane interface the concentration of L-Trp is diminished... 

Figure 2.2. Schematic representation of liquid chromatography experiment.

For the system cellulose acetate (E-398-3)/sodium chloride/water, the retention volume data of [= 3.578 x 10 m and [Vi ]waier = 4.050 x 10 m were obtained from liquid chromatography experiments. The total surface area of the cellulose acetate powder packed in the chromatography column is known to be 708.7 m. Calculate T/cAb Rnd compare the result with the value obtained in Example 3. 

The research indicates a good compatibihty in the ethylcellulose/cellulose acetate system, whereas the thermal stabihty of mixtiu-es is improved compared to that of pure ethyl cellulose [142], Thus, this blend met the best equilibrium conditions at the membrane-solution interface of membrane separation in liquid chromatography experiments. In this context, knowledge on the interaction force between solute and interface of the membrane is necessary. It is observed that the interfacial adsorption properties and hydrophilidty of ethylcellulose are improved when blending the solution with cellulose acetate, and also that the alloys are superior to ethylcellulose in the separation efficiency for non-dissociable polar organic solutes. The obtained results are useful especially for orientational membrane fabrication. 

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