Thursday, November 6, 2008

Chromatography: Forensics

The forensic uses of chromatography are varied and commonplace. With the popularity of forensic-based shows like CSI (can you believe CSI: Vegas is losing Grissom), many layman have at least a surface understanding of forensics. Chromatography, defined as “a physical separation method in which the components of a combination are separated by differences in their distribution between two phases, one of which is stationary (stationary phase) while the other (mobile phase) moves through it in a definite direction”, is a mainstay of forensic procedures and tests.

The Russian botanist Mikhail Semyonovich Tsvet (1872-1919) is often credited with the initial experiments into chromatography. He was born in Asti in Italy and attended the prestigious University of Geneva, where graduated with a B.S. degree from the Department of Physics and Mathematics. In 1903, while investigating a variety of compounds, he noticed the various compounds registered as distinctive colors under a UV lamp. Tsvet’s work was initially dismissed, due in large part to the fact that he only published his work in Russian, but benefited from a resurgence of interest in the 1930s.

Currently, there is a variety of chromatographic processes available. These include gas chromatography, liquid chromatography, ion exchange chromatography, and affinity chromatography. What this process allows, among various other benefits, is the precise separation of complex chemical mixtures using a color-coded matrix. The identification of chemicals by means of a color code has made chromatography very popular, especially at potentially messy forensic crime scenes.

Normally, the application of chromatography in a laboratory setting involves passing a mixture through a series of phases. The mixture passes from a mobile phase, through a stationary phase, and results in the isolation of the desired molecule or compound. This system can either be preparative or analytical, wherein preparative chromatography isolates compound for further study and analytical is concerned with measuring relative proportions.

The uses of chromatography are varied and accurate, making it a perfect match for law enforcement. As the forensic specialists forge forward with their investigations, stay tuned to your favorite crime show. You may hear them mention, as the dramatic music crescendos and your favorite stars pretend to be concerned, a chromatographical process.

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