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Detective Work: Fraud Detection

CREST Awards project

CREST Bronze Award – typically 10 hours of project work Investigate Archimedes’ method for non-destructive testing of metals

When Archimedes stepped into a full bath it overflowed. This gave him a clue to solving a king-sized problem: how to determine whether or not the new royal crown was pure gold. “Eureka!” he cried, meaning “I’ve found it!” Read about Archimedes to find out how the overflowing bath helped him to determine the density of the crown, and thus solve the problem. In this project you will use a modern version of Archimedes’ method to investigate the composition of copper, silver and gold items.

Eureka can

Doing experiments in a public bath is not very convenient, so a portable version of a bath was developed. It is called a ‘Eureka can’ after Archimedes’ exclamation. Find out what a Eureka can (or specific gravity can) is used for, and how to use it.

Copper coins

Work out how to use a Eureka can to prove that a modern 1p or 2p ‘copper’ or ‘bronze’ coin is neither pure copper nor bronze. Are modern 1p and 2p coins made from the same metal? How does the density of these modern 1p and 2p coins differ from those minted before 1992? Suggest an explanation, and a reason why the composition of the coins was changed. (Hint: a magnet should help.) Were the original decimal coins (pre-1992) made from the same metal as predecimalisation pennies and halfpennies (1d and ½d)?

Silver coins

Devise a way to improve your method to make your measurements more precise. You need to be able to calculate the density of a coin to at least 3 decimal places. (Make sure that you understand the difference between ‘precise’ and ‘accurate’. Using a calculator to get an 8-figure answer does not mean the answer is accurate. You will probably need to discuss this with your teacher.) Use your improved method to compare 5p, 10p, 20p and 50p ‘silver’ coins;; show that the coins are not real silver. Are they all the same?

Testing gold

It’s most unlikely that anyone will lend you a crown to test, but you can follow in Archimedes’ footsteps at a more modest level using gold rings or pieces of jewellery. An important point about this method is that it is non-destructive testing;; you don’t need to damage the item. Find out about measuring the purity of gold in carats. Work out how to determine the carat value using your improved version of Archimedes’ method. Test some rings or jewellery to decide their carat value. Compare your results with the items’ hallmarks, if any. Find out how the purity of gold or silver is checked at an Assay Office before it is granted a hallmark. Just as in Archimedes’ day, this is an official test procedure as a precaution against goldsmiths and silversmiths cheating their customers.

For further information visit our website www.britishscienceassociation.org/crest



CREST Silver Award – typically 30 hours of project work Investigate the uses of chromatography in fraud detection

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.

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, 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. You have probably done chromatography with felt-tip pen inks and water, but cheques should be written in permanent ink or ballpoint pen. These inks aren’t water-soluble. 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.

Things to think about

Extracting the two inks from the cheque and which solvent to use to run the chromatogram (think about safety issues when choosing a solvent). How the colour-printed background on the cheque may affect your method and/or results; and how you will deal with this problem. The relative advantages and disadvantages of using paper chromatography and thin layer chromatography (tlc). How to match the forgery with a particular pen belonging to a suspect.

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(s) 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, car tax discs 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 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. 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?




Suspect Smarties®?

Dyes used for colouring food are strictly controlled. In Europe, permitted food colourings are given E-numbers, which must be stated in the list of ingredients. How can we tell whether a manufacturer is sticking to the rules? Have you ever come across counterfeit Smarties? How can you be sure? Chromatography to the rescue once more. A Smarties® packet lists the E-numbers of the colourings they contain. Investigate whether the sweets really do contain only these permitted colourings. You will need to research a suitable way of extracting the dyes in fairly pure form, since other substances in the sugar coating interfere with the chromatography, preventing the dyes from separating properly. You will also need known samples of the permitted dyes to run alongside your extracts.

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. As before, you need to think about: Extracting dyes from the carpet fibres, both natural and synthetic. Finding suitable solvents for the chromatography, since the dyes are unlikely to be water-soluble (again, consider safety issues when selecting a suitable solvent).

Professional methods

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.




CREST Gold Award – typically 70+ hours of project work Investigate the adulteration of food and drink

Periodically a new food scam hits the headlines… 2004 Specially purified water turned out to be bottled tap water – and contained a suspected carcinogen (cancer-causing chemical). 2003 DNA tests found horse and donkey meat in salami. 1985 Several Austrian wine producers added ‘antifreeze’ to sweeten their wine. 1981 Adulterated olive oil killed over 400 people in Spain. These stories come to light because chemical analysis detects the problem. Unfortunately the media often misunderstand the science and spread scare stories that are far from the truth. In this project you will concentrate on the scientific detection aspects. You should make contact with professional scientists who can advise you about the methods you might use, and show you the instrumental techniques they use themselves. Starting points could include the Food Standards Agency, Trading Standards and public analysts.

A lack of concentration

A common form of adulteration (not necessarily illegal) is to dilute a product. Cheap bleach, vinegar, washing-up liquid etc. are sometimes watered down versions of the original. Devise a method for performing ‘consumer tests’ on one such product. Determine the concentration of several brands over a range of prices, and compare their value for money. Are ‘Value’ brands actually good value? CARE: some of the reagents used are hazardous Extend your investigation to a product that is not a simple aqueous solution, for example to determine the percentage of cocoa solids and/or cocoa butter in various brands of chocolate.

Pure as a virgin?

The olive oil that killed 402 people in Spain had been deliberately mixed with oil declared unfit for human consumption. Even ‘extra virgin’ olive oil is often far from pure. A 1995 study by the U.S. Food and Drug Administration found that only 4% of the 73 brands tested were pure olive oil. The rest were adulterated with cheaper vegetable oils. Research the differences between various vegetable oils (including olive), and ways to measure these differences by chemical analysis, such as ‘saponification value’ and ‘iodine value’. Thus deduce how to distinguish between olive oil and others. Using this information, devise procedures for determining whether a sample of olive oil has been adulterated with other vegetable oils.

The ‘antifreeze’ scare

Austria now has some of the strictest wine laws in the World, after a scam almost destroyed their wine industry. The media reported that some producers had added antifreeze to their wine – not quite true, but a fraud nonetheless. Antifreeze is ethylene glycol. What they had added was diethylene glycol, to make rather poor wine sweeter and smoother, with more ‘body’. For further information visit our website www.britishscienceassociation.org/crest



Find out the properties of diethylene glycol (2,2-dihydroxyethoxyethane). Devise ways to detect it, at about 1% concentration in 10% aqueous ethanol (roughly equivalent to wine). Your tests must be able to distinguish between diethylene glycol and other compounds that one would expect to find in wine. Research instrumental analytical techniques to decide which would be the most suitable to detect, and measure, diethylene glycol in wine. Your professional contact may be able to show you such an analysis in practice.

Something fishy

“Fish Fingers: 100% cod” says the label;; but cod is increasingly expensive. Who would know if an unscrupulous manufacturer were to substitute a cheaper fish? Similarly, how did the Food Standards Agency discover that salami contained horse and donkey meat? Like so much biological detective work, the answer lies in DNA. Find out about electrophoresis, and how it is used to establish biological identity. You will also need to learn how to extract DNA from a biological sample. Use electrophoresis to compare known samples of cod and other white fish. Then investigate unknown samples provided by your teacher. Some of these should be a single fish, others a mixture. Your task is to detect which is which. CARE: make sure your electrophoresis equipment is of a safe design.

Your results

In the above investigations you have undertaken the role of an analyst commissioned to test the products. Produce a report for your customer, detailing your evidence and conclusions. Remember, your evidence must stand up in court, so you need to make sure that you can answer any objections that may be raised, and disprove any counterarguments.




Health & Safety considerations When you carry out experiments make sure you: (a) find out if any of the substances used or made, or any of the equipment or procedures are hazardous (b) carry out a risk assessment (in other words, think about what could go wrong and how serious it might be) (c) decide what steps you need to take, if any, to reduce the risks. For example, by wearing personal protective equipment, being aware of how to deal with any emergencies and so on (d) make sure your teacher checks your plans and risk assessment before practical work starts (e) if special tools or machines are needed, these should be used in a properly supervised workshop or D&T room. NOTE: Your teacher will check your risk assessment against that of his/her employer (i.e. your school or LEA). If no risk assessment exists for your activity, your teacher may need to obtain a special risk assessment (e.g. by contacting the CLEAPPS School Science Service.) This may take some time.
