Capillary experimental setup

The experimental setup for high-speed CZE can be seen in Figure 9.8. Highspeed CZE, or fast CZE (FCZE), yielded 70 000 to 90 000 theoretical plates for the separation of amino acid mixtures. Complete separation was achieved in under 11s, using a capillary length of 4 cm (24). 

FIGURE 4-23 Experimental setup for monitoring dopamine release by exocytosis, from a cell body. The microelectrode and glass capillary (containing the chemical stimulant) are micromanipulated up to the cell body. (Reproduced with permission from reference 82.)... 

The experimental setup is shown in Figure 9.23. The Pt-black catalyst film also served as the working electrode in a Nafion 117 solid polymer electrolyte cell. The Pt-covered side of the Nafion 117 membrane was exposed to the flowing H2-02 mixture and the other side was in contact with a 0.1 M KOH aqueous solution with an immersed Pt counterelectrode. The Pt catalyst-working electrode potential, Urhe (=Uwr)> was measured with respect to a reversible reference H2 electrode (RHE) via a Luggin capillary in contact with the Pt-free side of the Nafion membrane. 

Fig. 2.5.6 Schematic of the experimental setup used to monitor reaction kinetics with a multiple microcoil system. Two syringes on the pump inject the reactants into two capillaries. The reactants are mixed rapidly with a Y-mixer. After mixin g, the solution flows through the...

Instruments are controlled by information contained 1n the experimental setup file. For each type of instrument (shear history simulator, rotational viscometer, reciprocating capillary viscometer), the hardware 1s controlled so that the parameters of shear rate, temperature and time comply with the desired test conditions. This involves controlling devices such as pumps, bath heaters, valves and variable-speed motors. The setup and control parameters are recorded in the experiment file along with the resulting measured data. If necessary, the experiment can easily be repeated. 

In this group of methods the sample constituents can migrate differentially in zones through the capillary in a medium that can be either a gel (CGE) or an electrolyte (FSCE). Again, the experimental setup is similar to the one presented in Fig. 17.8. 

In FSCE the capillary is filled with only an electrolyte, usually a buffer to maintain the pH. The experimental setup remains similar to the one used for the previous methods and presented in Fig. 17.8. FSCE is currently the most applied technique in CE. The separation is based on... 

Fig. 1 Schematic representation of the experimental setups of the mobility-shift method and the Hummel-Dreyer method (A) the vacancy peak method and the vacancy affinity capillary electrophoresis method (B) the equilibrium-mixture method and the frontal analysis method (C) for drug-protein binding analysis. drug protein gg drug-protein complex Q buffer. (Reprinted with permission from Ref. 38. Copyright 1992 Elsevier Science.)...

Experimental setup for capillary electrophoresis. Courtesy of Bio-Rad Laboratories, Life Science Group, Hercules, CA. 

Fig. 12 Experimental setup for a HWG gas-sensing system utilizing a supported capillary membrane sampler, a HWG gas-sensing module, and a compact FT-IR spectrometer [50]...

Figure 1 is a schematic diagram of the experimental setup. The test section is a horizontal rectangular channel 40 mm in height (H), 160 mm in width (W), and 6,000 mm in length (L). The rectangular channel is completely constructed of transparent acrylic resin, as shown in Figure 2. Tap water and air are used as the gas and liquid phases, respectively. Water is circulated by a 2.2 kW pump fed by a water reservoir 4.2 m away. Air bubbles are injected into the horizontal channel from the upper inner surface of the channel. An array of capillary needles produces bubbles 10-100 mm in length. Before the air and water are mixed, their volumetric flow rates are measured. After leaving the horizontal channel, the gas-liquid mixture is dumped into a tank that acts as a bubble remover when the liquid phase is recirculated it is free of bubbles. At the end of the horizontal channel tracer particles are added to the water to act as ultrasound reflectors. The mean particle diameter is 200 pm and the particle density is 1020 kg/m3. These tracer particles are assumed to...

Figure 12.4 depicts schematically the experimental setup used in capillary flow studies. The primary application of the discussion that follows is in capillary viscometry, which is useful to die design. The ratio Rr/R should be greater than 10, so that the pressure drop due to the flow in the reservoir can be neglected.1 The reservoir radius cannot be too large, though, because the time required for uniform heating of the solid polymer load would be too long (see Fig. 5.6). Long heating cannot be used for sensitive polymers such as polyvinyl chloride (PVC), which readily degrade thermally.

Fig. 12.4 Experimental setup for capillary flow showing reservoir, entrance, fully developed, and...

Presently a commercially available two stage vacuum system comprising a membrane (Pfeiffer MVP 006-4) and a turbo pump (Pfeiffer HiPace 10) in combination with a pressure sensor (Leybold Vacuum Ionivac ITR 90) establish a pressure of about 0.1 Pa in the system. Three electric valves are used to control the gas flow into the capillary system and for the bypasses. The use of macro devices simplifies the handling of the experimental setup and also the electronic control. Pressure drops for plasma and sample gases are accomplished by an appropriate combination of capillaries with different diameters and lengths as described in Sect. 4. 

Figure 1. Experimental setup of the capillary electrophoresis/radioisotope detector system. The inset shows the positioning of the CdTe probe with respect to the capillary tubing. The 2-mm Pb aperture is not shown in this illustration.

Using an erythrocytes-containing medium for perfusion one has to take into account the putative involvement of the erythrocytes themselves with respect to uptake of the candidate compound. Therefore, not only the erythrocyte-free perfusate but also the erythrocytes fraction should be included in the analysis of the candidate compound, separately. In our hands the model of isolated perfused liver is metabolically active for up to 3 hours and during this time no decline in hepatic metabolic activity becomes obvious. However, bile flow declined during the perfusion experiments. Therefore, our total perfusion time of isolated livers in our standard experimental setup is limited to 2 hours. The tissue level of the candidate compound analyzed after 2 hours in the liver is a measure for the total amount of compound in the whole organ. This does not necessarily mean the presence of the candidate compound in hepatocytes but additionally in the capillary and biliary space of the liver. 

Electrophoresis — Movement of charged particles (e.g., ions, colloidal particles, dispersions of suspended solid particles, emulsions of suspended immiscible liquid droplets) in an electric field. The speed depends on the size of the particle, as well as the -> viscosity, -> dielectric permittivity, and the -> ionic strength of the solution, and it is directly proportional to the applied electric field. In analytical as well as in synthetic chemistry electrophoresis has been employed to separate species based on different speeds attained in an experimental setup. In a typical setup the sample is put onto a mobile phase (dilute electrolyte solution) filled, e.g., into a capillary or soaked into a paper strip. At the ends of the strip connectors to an electrical power supply (providing voltages up to several hundred volts) are placed. Depending on their polarity and mobility the charged particles move to one of the electrodes, according to the attained speed they are sorted and separated. (See also - Tiselius, - electrophoretic effect, - zetapotential). 

The experimental setup, procedure and analysis are described in detail by Pfohl et al.11-12. For the systems containing acetone and 2-propanol, two different apparatuses have been used. Each apparatus (-1000 cm3, static-analytical method) is placed in a thermostated bath and equipped with sampling capillaries, thermocouples and high-precision pressure transducers. 

Although affinity capillary electrophoresis (ACE) in its classical mode (one of the reagent is dissolved in a BGE, another is injected) is the most widely used technique in the literature, other capillary electrophoretic methods exist which are even more favorable concerning the information about binding parameters obtainable the Hummel-Dreyer (HD) method, frontal analysis (FA), the vacancy peak (VP) method, and vacancy affinity capillary electrophoresis (VACE) (see, e.g., Refs. 49-57). All the methods need as a precondition that the equilibrium between the reactants (say, protein P, drug D, and complex formed PD) is established rapidly compared to the dislocation of the electropho-retically migrating zones. The experimental setup of the HD and the ACE methods is identical, and so is the setup for the VP and the VACE methods. FA differs from all the other techniques. 

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