Capillary Electrophoresis 2 High-Voltage Power Supply

A capillary electrophoresis instrument includes two buffer vials, sample vial, fused silica capillary column, high-voltage power supply, detector, and a... 

A schematic representation of a CE system is presented in Figure 9.1. In this diagram, the CE components have obvious counterparts to those found in slab gel electrophoresis. Instead of buffer tanks there are two small buffer reservoirs, and the capillary takes the place of the gel (or more accurately, a gel lane). The capillary is immersed in the electrolyte-filled reservoirs, which also make contact with the electrodes connected to a high-voltage power supply. A new feature to the conventional gel electrophoresis format is the presence of an online detection system. 

Capillary electrophoresis (CE) instrument is quite simple. A CE, at its core, is merely a high-voltage power supply (capable of voltages in excess of 30,000 V), capillary (approximately 25 to 100 pm inner diameter), buffers to complete the circuit (e.g., citrate, phosphate, acetate, etc.), and a detector (e.g., UV-Vis). There are additional complexities, of course, but at its heart, the CE is a simple instrument. 

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. 

Jackson, D.J., Naber, J.F., Roussel, T.J., Jr., Crain, M.M., Walsh, K.M., Keynton, R.S., Baldwin, R.P., Portable high-voltage power supply and electrochemical detection circuits for microchip capillary electrophoresis. Anal. Chem. 2003, 75, 3643-3649. 

Figure 4-33. Block diagram of capillary electro- carried out close to the cathode in a region phoresis equipment. Capillary electrophoresis where the capillary is transparent, allowing equipment consists of a thermostatted capillary photometric or fluorimetric analysis of the whose ends are placed in the electrode buffer eluate. The detector system is linked either to a chambers these contain the electrodes attached recorder/integrator or to a PC. to a high-voltage power supply. Detection is...

Figure 10.1. Schematic representation of a capillary electrophoresis instrument. A, electrolyte reservoirs B, platinum electrodes C, fused silica capillary D, detector cell E, high-voltage power supply.

Capillary electrophoresis (CE) was first introduced in 1983. Since that time there have been numerous reports of the determination of amino acids by CE. The simplest system consists of a high-voltage power supply, two buffer reservoirs, a transparent plastic safety box, two platinum wires, a detector, and a fused silica capillary. The capillaries employed have very small diameters, generally between 5 and 100 pm. In general, the same types of detectors are used as for liquid... 

Fig. 6. Generic Diagram of a Capillary Electrophoresis System. H TS - high-voltage power supply unit, E - electrodes, RB - reservoirs of the electrolyte buffer of sample vessels, C -separation capillary, D - detector.

Capillary electrophoresis is an analytical technique which enables efficient and rapid separation of ionic compounds under the influence of an electric field. The analysis is conducted in a fused silica capillary that is filled with an electrolytic solution, or buffer. Each end of the capillary is placed in a buffer reservoir along with electrodes attached to a high-voltage power supply. The power supply is then used to apply an electric field, up to 30 kV, between the two reservoirs. A schematic of a typical CE instrument is shown in Fig. 10. 

DSP of Biomolecules, Fig. 2 Scheme of a capillary electrophoresis. A CE instrument consists of a high-voltage power supply, a silica capillary with an internal diameter ranging from 20 to 200 pm, two buffer reservoirs, two electrodes connected to the power supply. 

Commercially available CE instruments consist of (i) an electrolyte filled capillary which passes through the optical center of a detector, (ii) a sample injector, (iii) a high voltage power supply, and (iv) an auto-sampler. The entire instrument is computer controlled. Figure 12.22 is a schematic drawing of the typical capillary electrophoresis system. 

D.J. Jackson, et al.. Portable high-voltage power supply and electrochemical detection circuits for microchip capillary electrophoresis. Analytical Chemistry 75 (14) (2003) 3643-3649. 

FIGURE 24.7 Sequential injection analysis-capillary electrophoresis manifold with contactless conductivity detection (SIA-CE-C D). C D capacitively coupled contactless conductivity detector DW deionized water ES electrolyte solution GI grounded interface HC holding coil HV high-voltage power supply ND needle valve S sample SC separation capillary SI syringe SLl 1 M NaOH SL2 1 M HCl SP syringe pump SS safety switch SV selection valve VI and V2 solenoid valves W waste. 

The instrumental arrangement commonly employed in capillary electrophoresis is shown in Figure 12.1. With untreated silica capillaries, electroosmosis causes the buffer to flow from the anode to the cathode. Samples are introduced at the anodic end, and an on-column or post-column detector is placed at or near the cathodic end of the capillary. The high-voltage produced by the power supply and present in the anodic buffer reservoir is enclosed in a protective shield. 

---