What Are the Uses of Paper Electrophoresis?

Paper electrophoresis attained widespread use in the 1950s. It is a scientific method of separating a substance to determine its composition. Wide-ranging ramifications of this method and resulting newer electrophoresis technologies have served scientific and other industries as well.

How It Works

• As described by Clive Dennison in his book, "A Guide to Protein Isolation," in paper electrophoresis, a strip of filter paper is saturated in a liquid buffer solution to encourage electrical conductivity. Each end of the paper strip is placed in a reservoir containing more buffer solution. A sample of a substance to be analyzed is placed in the middle of the paper strip. Electricity at relatively high voltage is then sent through the paper strip. As a result, the molecules in the sample will separate into bands depending on their electrical charge. Scientists can then determine the composition and proportions of the original sample.

Scientific Applications

• The main use of paper electrophoresis is that of analysis. Scientists have used this technique in many scientific experiments as a way to prove or disprove hypotheses or to determine the efficacy of drug treatments. According to the Encyclopedia of Public Health, scientists use a specific paper electrophoresis test, called the Western blot, to detect the presence of human immunodeficiency virus (HIV) in blood samples. In addition, other blot tests help detect the type and amount of DNA and RNA in sampled materials, which has major implications for forensic investigations. Furthermore, paper electrophoresis can be used for testing suitability of municipal water supplies, toxicity of waste water and other environmental components.

Drug Testing

• The drug-testing industry has used paper electrophoresis to determine the presence of illegal or recreational drugs in job applicants and crime suspects. Furthermore, sports authorities such as the International Olympic Committee have used the technology to screen athletes suspected of ingesting illegal performance-enhancing supplements.

Ink Analysis

• Inks such as those used to print currency and checks consist of diverse chemical makeups. Investigators and forensic scientists have used paper electrophoresis since the 1950s to analyze inks. Results of these tests help determine the authenticity of suspected counterfeits, forgeries and other fraudulent documentation.

E-Paper

• E Ink used electrophoretic technology in pioneering electronic paper display (EPD) technology. The company invented an electronic ink that consists of millions of minute microcapsules, about 100,000 per square inch of paper, containing a clear fluid in which positively charged particles of one color and negatively charged particles of a contrasting color reside. When an electric field is applied to a paper or film printed with the ink, all the particles of one charge rise to the surface, depending on the polarity of the electricity. For example, if all the positively charged particles rise and they are black, the printing will show up as black. Reversing the electrical field causes the particles of the other polarity and color to rise.

  This technology is being used for watches, mobile phones and other handheld electronics, as well as for signage. The low voltage required makes these items tremendously inexpensive to operate.