Crime Scene InvestigationForensic scientists collect evidence from present crime scenes in the aim of finding perpetrators of crimeThey collect small samples of evidence left behind at the scene and use them to reconstruct events that led to the crime occurring.Use some investigative skills to solve the following crimesINK PEN MURDERWHO STOLE THE SWEETIES?

We have reason to suspect dirty deeds at work!

Mr Scribbler, the chief animation assistant, on the new Disney film was found murdered at his drawing board late last night.

The murder weapon is thought to be a pen, as the only clue left behind was a pool of ink and ink stains on Mr Scribbler’s shirt.

Our only hope, in the form of Mr Labcoat, our resident scientist, has gone on holiday for two weeks and we need to track a our culprit before he strikes again!

My only hope is to ask you, our new forensic science recruits, to solve the mystery of the ‘Ink Pen Murder’.

Take the challenge!!!!!!!!

ChromatographyUsing a separating technique called ‘chromatography, we might just be able to find the murderer from our list of suspects.We can use chromatography to separate very small quantities of substances, which vary in different solubilities in different solvent.Using a special type of paper called ‘chromatography paper’, which you can put the substances onto, and by placing the paper into a solvent, the different substance will separate on the basis of how well they dissolve in the solvent.

How it separates inksInk from pens; usually contain different types of dye, which make up the colours. These dyes have different solublities in the solvent. Those, which are the most soluble in the solvent, travel the furthest, carried by the solvent and coloured traces can be seen.This indicates that if we can find exactly the same chromatogram using a range of inks from our suspects we will be able to work out who the murderer is, by comparing it to one carried out by Mr Labcoat on the sample found at the scene before he left.The instructions on how to carry out this investigation can be found opposite, should you chose to except the mission………….GOOD LUCK!!! Inspector Gadget

You will need:

    Safety goggles    A piece of chromatography paper    A beaker containing a solvent to run the chromatogram*    Evidence inks from suspect A, B, and C    Sample of ink found at the crime scene ! Safety:Ethanol, which is used in the solvent, is highly flammable and harmful. Take care when using it.

To carry out the investigation, follow these instructions:

    Place the chromatography paper on the bench in front of you. Using a ruler and a pencil draw a line across the bottom of the paper 2cm from the base. Make sure this line is parallel.    Using a pencil mark four dots on the line, evenly spaced out.     Put your three samples from your suspects on the first three dots, a small drop will be enough and then the sample of ink from the scene of the crime on the last spot. Mark at the top which sample belongs to who, for your own reference.    Stand the paper in the solvent and let the solvent run until it has almost reached the top. (See the diagram on next page).    Lift out the chromatography paper and leave it to dry.    Compare the evidence and solve the mystery. If the traces match…….then they are the murderer.

Diagram of apparatus for chromatography

Pencil line

Solvent

Chromatography paper

Samples of ink

Beaker

Finger prints