Criminal investigations use chemistry to routinely solve crimes. Kidnapping crimes often involve ransom notes hand written in ink. In this case, the perpetrator left behind such a note. To find out what ink was used on the note, chromatography was performed. Chromatography is used to separate a mixture of components to observe its components substances. In this investigation, the researchers had to figure out which pen was used to write the letter, therefore, what is known about ink had to be deducted. Black ink is a mixture of several different colors. When using chromatography, these colors can be separated. To find out which ink pen was used in the ransom note, the experimenters had to perform a chromatographic experiment.
Experimental.
Materials:.
4 black ink pens.
12 sheets of chromotography paper.
Large beaker.
Medium sized beaker.
Small beaker.
A ruler.
Ink sample from the crime scene.
20% ethanol solution.
50% ethanol solution.
90% ehtanol solution.
paper towels.
Procedure:.
Upon entering the laboratory, the experimenters gethered their materials. First, the ethanol solutions were poured into their respective beakers. The 20% was poured into the large beaker, the 50% was in the medium sized beaker and the 90% was poured into the small beaker. The pens were then gathered and the chromotography paper was laid out in a grid-like fashion on top the desk. Paper towels were then laid across the back to discard the used up chromotography papers. .
After the four ink pens were obtained, the first thing the experimenters did was place a dot about 2.5 cm from the end of the chromotography paper. Out of all the pens, the ink from the yellow pen was tested first, follwed by the green, blue, and pink pens in that respective order. Each ink was tested individually on its own piece of chromotography paper. Each piece of chromotography paper was placed individually in the 20%, 50% and 90% ethanol solutions one at a time.