Introduction

Electrophoresis is one of the most powerful tools in the arsenal of separation scientists. It is commonly employed in the field of biochemistry, where separation of complex mixtures of proteins or nucleic acids is a continuing challenge. Numerous variants of elec-trophoresis have been described with the goal of optimizing the speed and effectiveness of the separations. One important electrophoretic variable is the separation matrix. It provides the retarding forces, or sieving qualities, that counter the electrophoretic transport. These forces can ultimately effect the separation and can be altered by the matrix type or concentration. Cross-linked or linear forms of polymers such as agarose or acrylamide are common choices. Different formats for the electrophoresis medium can also have dramatic effects on the resolution and separation time. This is exemplified by recent uses of microcapillary formats which greatly speed up separations. Another component that dictates the speed and resolution of electrophoretic separations is the charge-carrying buffer ion. The buffer is a universal component of electrophoresis, independent of gel constitution or format. This component is often overlooked, though attention to this aspect can be beneficial in developing electrophoresis-based separation techniques.

Proper buffer selection offers several practical advantages, including optimum separation times, in

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creased band concentration and reduced effects of diffusion. The resolution of closely migrating species results from the proper choice of the pH, concentration, and type of buffer ion. These physical characteristics define the conductivity of the electrophoretic medium and affect the transport of the molecules to be separated. Inorganic ions, such as chloride anion, have high conductivities in comparison to the ionized form of weak acids and bases. Such high mobility ions offer little advantage when used for the elec-trophoretic separation of large, less mobile bi-omolecules but slower-moving ions, such as those of weak acids or weak bases, are more useful choices. These not only buffer the pH but, due to the slower mobility of these ions, lead to better separation of charged macromolecules.

Zonal electrophoresis utilizes a single buffer in the gel and reservoirs. An alternative to the continuous buffer, zonal separations is a discontinuous system where multiple ionic components are used. The presence of multiple ionic components in electrophoresis leads to discontinuities in the voltage gradient, pH and ionic strength due to the different physical mobilities of the ions involved. These different mobilities lead to the formation of discrete zones of ions that, under equilibrium conditions, travel at a constant rate in an applied electric field. Adjustment of these mobilities involves alteration of the ion concentration and potential gradient of the zone. Sharp boundaries can exist between these zones, with the ionic concentration being dictated by the Kohlrausch regulating function. The technique is similar or identical to a number of electrophoresis techniques that are known as discontinuous multiphasic, multizonal,

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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