Click to edit project
Click to edit project description
Detect fraud using chromatography Chromatography literally means ‘colour writing’. The results of an analysis are ‘written’ as a series of coloured spots. The positions of the spots help the analyst to decide what the original sample contained. If the results aren’t what they should be, something is wrong – maybe a fraud. One advantage of chromatography is that it needs only tiny samples for testing. In this project you will use chromatography to detect forged cheques and other documents and various types of counterfeit goods. Getting Started Checking cheques: Banks advise customers to leave no gaps when writing a cheque, to make it more difficult to alter the words and numbers, however, we all make mistakes. To correct a mistake, you need to alter the writing and sign the alteration. So, what’s to stop a fraudster altering a cheque and forging the person’s signature? The fraudster will use a different pen. The ink may look the same, but chromatography can detect the difference. Your first challenge is to devise a reliable method of using chromatography to decide whether the writing on a cheque has been altered using the same or a different pen. Find out about relative frequency values, and how they can be used. Try out your method using real cheques rather than plain paper, so you can see the effect of the coloured background. Dodgy documents: It’s not only cheques that are open to forgery. With modern office equipment, almost any document can be copied – certificates, passports, visas etc. Once again, detecting differences in the inks is one way to spot forgeries. All colour printers use three transparent inks (cyan, yellow, magenta) plus black, but same colour doesn’t necessarily mean the same dyes. Print the same multicoloured document on several different makes / models of printer: • Experiment to find the best solvents to extract the inks and run TLC plates. Make sure the solvent is safe. Click to edit project description • Compare the inks from the same part of the document printed on different models. Are any particular shades of colour better than others for showing up differences? • Investigate whether it is possible to deduce which make and/or model of printer was used to print a document. • What difference does it make if the document was printed on a printing press? Why? Things to think about How will you extract the two inks from the cheque and which solvent will you use to run the chromatogram? Are the solvents safe? Will the colour-printed background on the cheque affect your method and/or results and if so how you will deal with this problem? What are the relative advantages and disadvantages of using paper chromatography and thin layer chromatography (TLC)? How can you match the forgery with a particular pen belonging to a suspect? Useful Resources You should try to make contact with professionals involved in this type of detection work, for example trading standards officers, public analysts and forensic scientists. Find out about the chromatographic techniques that they use, and compare them with your own methods. Antique antics: Genuine antiques have rarity value and are expensive. Reproduction antiques (modern copies) are much cheaper. They can be made to look old, even though they are newly made. What if an unscrupulous dealer tried to pass off a reproduction Persian carpet as an antique? How could you tell? A reproduction carpet is probably dyed with modern dyes - a genuine antique carpet cannot be. So, analysing the dyes is the key. Even if you are lucky enough to have an antique carpet at home, don’t cut bits off it for this investigation! You can study the principle using samples from a carpet shop. Find carpet samples whose colours match the colours of some household fabric dyes. Your task is to determine whether the dyes in the carpet fibres are the same as the fabric dyes.
