Experimental setup power supply

Capillary Zone Electrophoresis. The primary advantage of capillary electrophoresis can be found in the simplicity of the instrument. Basic experimental components include a high-voltage power supply, two buffer reservoirs, a fused silica capillary, and a detector. The basic setup is usually completed with enhanced features such as multiple injection devices, autosamplers, sample and capillary temperature controls, programmable power supplies, multiple detectors, fraction collection, and computer interfacing. 

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 for synthesis of nanoparticles by pulsed electrical discharge submerged in a liquid consisted of a power supply system, a glass vessel and a water cooling system. The optimum distance between the electrodes was kept constant at approximately 0.3 mm to maintain a stable discharge. The power supply provided several types of discharges. The experiments described... 

An understanding of the operation of the SECM and an appreciation of the quantitative aspects of measurements with this instrument depends upon an understanding of electrochemistry at small electrodes. The behavior of ultramicroelectrodes in bulk solution (far from a substrate) has been the subject of a number of reviews (17-21). A simplified experimental setup for an electrochemical experiment is shown in Figure 1. The solution contains a species, O, at a concentration, c, and usually contains supporting electrolyte to decrease the solution resistance and insure that transport of O to the electrode occurs predominantly by diffusion. The electrochemical cell also contains an auxiliary electrode that completes the circuit via the power supply. As the power supply voltage is increased, a reduction reaction, O + ne — R, occurs at the tip, resulting in a current flow. An oxidation reaction will occur at the auxiliary electrode, but this reaction is usually not of interest in SECM, since this electrode is placed sufficiently far from the UME... 

Recently a method has been developed to determine the average flow velocity by measuring the electric current in a microchannel under electroosmotic flow [6, 7]. The experimental setup is shown in Fig. 2 and consists of a microchannel, a high-voltage power supply, and a data acquisition system. The microchannel and reservoir 2 are initially filled with an electrolyte solution that has a slightly different concentration than reservoir 1 (cj — C2 = 5 %). The concentration difference must be small so that the zeta potential and ionic concentrations are nearly uniform throughout the microchannel. 

Ensure the complete electrical isolation of electrical equipment and power supplies. Enclose all power supplies in a manner that makes accidental contact with power circuits impossible. In every experimental setup, including temporary ones, employ suitable barriers or enclosures to protect against accidental contact with electrical circuits. 

Fig. 9. Experimental setup for impedance measurements with electrochenucal control of membrane impedance platinized platinum electrodes (a) constant voltage power supply, (b) gold minigrid electrode (c) polypyrrole film, (d) 1 M KCl solution (e) constant current ac circuit, (f). At right is a microscopic view of membrane, illustrating effect of membrane potential on ionic resistance (reprinted with permission ft om Ref.

Fioure 7.30 Experiments to illustrate the effects of stray current showing (a) the experimental setup containing a DC power supply plus two steel nails partially immersed in a dilute saline solution and connected to the positive (left) and negative (right) posts of the DC supply the effects of imposing a DC current on the nails (b) after five and (c) ten minutes. 

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