This is the first post in a series on Forensic Science, one of approximately 3 tracks of study I have on this site. (Others being Deduction and Persuasion at the time being. I plan to introduce Body Language sometime, as well as Memory). My goal is to have as many tracks as possible, not to mention some as-yet uncategorized, unnumbered posts such as Mind Palace and Color Psychology in Persuasion. Here at WoMD I definitely need to organize a bit better!
The first topic is Organic Analysis. It is very important in detecting substances at a crime scene. Organic analysis uses methods from chemistry and biology to find different substances in a compound or mixture and compare unidentified substances from a scene to known ones.
If you have any chemistry background, you will know a bit about matter and compounds. For those unfamiliar, here is a simple description: Elements and Compounds
From there, we have organic compounds. An organic compound is any compound that contains the element carbon. All others are inorganic, and are therefore analyzed using different methods. Methods used for analyzing organic compounds include chromatography, electrophoresis, and spectrophotometry.
Chromatography separates mixtures into their different ingredients by bringing them from one place to another. It is often used with unknown mixtures of illegal drugs. The substance is attracted to something that stays in one place and is moved by another substance.
For example, gas chromatography moves one gas towards a liquid through another gas. It takes place in a device called a gas chromatograph (x) which includes a detection device. This detector creates a chromatogram, which is a graph comparing recorder response with time.
If an item is a solid, a process called pyrolysis will be used in order to decompose it into different gases. For heat-sensitive items, high-performance liquid chromatography, which works at room temperature, is used. Thin-layer chromatography, in which the substance is attracted across a solid plate, is used for solid and liquid items.
Electrophoresis is similar to thin-layer chromatography, only it uses electricity rather than a moving liquid to move the substance. This is often used for blood, proteins, and DNA. An electrophoresis process used to compare DNA samples for similarities and differences is called a polymerase chain reaction, or PCR for short.
Spectrophotometry measures the light absorption spectrum of a substance. It is similar to chromatography in that the light absorption spectrum of a substance, like the distance traveled of a chromatographed substance, can be compared to a known substance. A spectrometer is far more complex than a chromatography device and would take much longer to describe, so here's a more in-depth description: Spectrometer. Mass spectrometry allows for a completely unique pattern to be made for a substance while others are less exact. Chromatography is often done before or alongside spectrophotometry.
Although spectrophotometry and electrophoresis require expensive lab equipment and probably some training to use, chromatography can be done at home.
At-Home Chromatography
What You Need:
-paper towels
-black pen or marker
-disposable cup
-water
Instructions: Fill the cup with water. Tear the paper towel into strips, and use the marker to draw a line across the bottom of each one. Hang each strip on the side of the cup so that it dips into the water. Let it sit awhile. Observe the paper towel strips.
(Though I don't like to give away all the results of a science experiment that I am instructing somebody on, it is important to know a bit of what will happen. The black ink will separate into different sections.)
That should be enough information for the first topic! Next, I will likely cover inorganic analysis, as it seems to be the most rational transition.
Signing off,
SM
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