Forensic chromatography

Today Ashmansworthy class have been learning how chromatography can be used to solve crimes. After our success in separating solids last week, today we learnt how to separate the different coloured components of ink using the process of chromatography. Dots of ink are placed on absorbent filter paper , which is then moistened with water. The water travels across the ink dissolving it, and carries the pigments different distances. The different colours of pigment which make up the coloured ink in a pen dissolve at different rates and produce their own unique pattern. This “fingerprint” can be used to identify exactly which type of pen was used to write, for example, a ransom note or a message from the donut thief. You can then test the different suspects’ pens to find out who the culprit is. Find out more here (clip 20):

Who stole the donuts?

The children used chromatography to investigate different types of pens and different types of ink. They also tried using different types of paper such as kitchen roll, paper towels, writing paper and tracing paper to see what happened. They found out that the more absorbent papers were the most effective at separating the ink, and ink which was not water soluble didn’t separate at all.



5 responses on Forensic chromatography

  1. This was a great activity because I liked how it looked when we put water on it, how it spreads. Also it would help with a crime because if someone wrote a letter saying they stole their cookie or something and you will see all sorts of different pens so you may see someone using the same pen that you put in water and that is the person who stole your thing. How to do that is put the note in water see it spread and get some different pens draw a dot with all of the pens and put water on them all in the same piece of paper but you must draw a line at the bottom. When you done that and all the ink is spread out you find which ink is the same one as the ink on the note so compare the ink and that is your subject. that is how you will solve a crime. best science yet! :)

  2. I loved this because it looked so cool and the colours spread and you could see lots of different patterns and also you could do a lot of experimenting with the colour and the different types of paper and different pens. It doesn’t work with paper that doesn’t soak up water because the colour doesn’t spread.

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