Murder in the lab

This session should take four hours. 

This event gives learners a flavour of state of the art analytical techniques that are used in forensic science, which learners may know something about from television. You will find the kit list, safety instructions, and in depth procedure points included on the download document below. 

Session timings

09.30 Reception and welcome.

10.00 Introduction to the crime scene. Advise learners to read the worksheets thoroughly before starting the activity.

10.15 Analytical laboratories.

Sub-group 1 Activity/Demonstration

HPLC separation of the saliva sample and coffee sample (identify caffeine and an unknown).

Sub-group 2 Activity/Demonstration

GC-MS identification of unknown as brucine. Demonstration given and supplied with a chromatogram.

Sub-group 3 Activity/Demonstration

CE identification of unknown is run and separated into its enantiomers to establish if its source is natural or synthetic.

Sub-group 4 Activity/Demonstration (incident room)

ICP-AES analysis of soil from the laboratory floor and each of the suspects shoes.

11.15 Each sub-group reports back findings (incident room).

11.30 Sub-groups report back findings to the main group. Learners are asked to make comments and suggest the identity of the murderer. The police officer summarises the evidence and arrests the suspect (on suspicion).

11.45 Fingerprinting by community police officer. Talk on role and career opportunities for chemistry graduates in forensic science.

12.45 A presentation on career opportunities given by an industry representative. Alternatively, a talk from a student about their route into chemistry and an opportunity for learners to ask them questions about their experience.

Scenario

This event gives learners a flavour of state of the art analytical techniques that are used in an area of chemistry, which many students know something about from television.

Procedure

High pressure liquid chromatography (HPLC)

1. Run your coffee sample.
2. Compare it to a sample of coffee made using the same coffee machine with the same brand of coffee, this is known as a standard. Is there anything unusual about the professor’s coffee? 
3. Run the saliva sample. Are there any similarities between the two samples? Why do you think this is?

Gas chromatography–mass spectrometry (GC–MS)

1. Run the coffee sample and isolate any unknown peaks.
2. Use the mass spectrometer to identify any contaminants. The technician will also tell you if the saliva sample contained the same compound.
3. What have you found in the coffee? Was it in the saliva as well?
4. Ask the technician to extract any unknown compounds and pass them onto the capillary electrophoresis technician.

Inductively coupled plasma atomic emission spectroscopy (ICP–AES)

1. Run an extract of the soil on the ICP, the technician will explain how he/she prepared the sample. Is there anything unusual about the soil? How does it differ from ordinary soil found on a typical suburban campus? Where do you think it might have come from?
2. The technician will also show you spectra from the victim’s and the suspects’ shoes. Record any observations.

Notes

Throughout the demonstration, in addition to technical information, the demonstrators should stress the importance of sampling, labelling and good laboratory practice.

It is advisable to obtain factual chromatograms and electrophoretograms for handing out, but alternatives can be used on the day.

Enantiomeric ratios may be different between synthesised and natural versions of a molecule.