A simple and fast technique to examine the surface of banknotes and identify counterfeits has been developed by scientists in Brazil and the US. Marcos Eberlin, one of the researchers at the University of Campinas, Brazil and Graham Cooks at Purdue University in West Lafayette, US, Eberlin and colleagues have devised a mass spectrometric technique that can give a chemical profile of banknotes in seconds. There is almost no sample preparation required, it is non-destructive, and the test can also reveal which counterfeit method was used to create the 'funny money'.
This new technique relies on using desorption ionisation mass spectrometry to test different spots on the banknote. The real banknotes show similar data (m/z ions), distributed evenly over the entire surface, despite age, denomination and colour pattern. This provides a fingerprint for the real banknotes. When the laserjet and inkjet notes are tested, a distinct set of ion markers can be seen and their fingerprint is quite different from the real money.
A summary on their jurnal article: Instantaneous chemical profiles of banknotes by ambient mass spectrometry.
By: Livia S. Eberlin, Renato Haddad, Ramon C. Sarabia Neto, Ricardo G. Cosso, Denison R. J. Maia, Adriano O. Maldaner, Jorge Jardim Zacca, Gustavo B. Sanvido, Wanderson Romão, Boniek G. Vaz, Demian R. Ifa, Allison Dill, R. Graham Cooks and Marcos N. Eberlin.
Using two desorption/ionization techniques (DESI and EASI) and Brazilian real, US$ dollar, and euro bills as proof-of-principle techniques and samples, direct analysis by ambient mass spectrometry is shown to function as an instantaneous, reproducible, and non-destructive method for chemical analysis of banknotes. Characteristic chemical profiles were observed for the authentic bills and for the counterfeit bills made using different printing processes (inkjet, laserjet, phaser and off-set printers). Detection of real-world counterfeit bills and identification of the counterfeiting method has also been demonstrated. Chemically selective 2D imaging of banknotes has also been used to confirm counterfeiting. The nature of some key diagnostic ions has also been investigated via high accuracy FTMS measurements. The general applicability of ambient MS analysis for anti-counterfeiting strategies particularly via the use of invisible ink markers is discussed.
"The work convincingly demonstrates a relevant application of these techniques in combating currency forgery," comments Niamh Nic Daeid, a forensic chemist at the University of Strathclyde in the UK.
"The next challenge will be to make this technology widely available to the forensic community as a robust and affordable technique."
As well as discovering fake money, Eberlin can see this method being used in a preventative way.
"We are already working together with the Brazilian Federal Police and the manufactures in Brazil to find the most effective way to add these chemical signatures, either in ink formulations or as invisible stamps or bar codes, as a new and hard to imitate security measure for Brazilian banknotes," he says.
Source: rsc publishing.
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