Dr Alan Ryder and colleagues in the National Centre for Laser Applications in NUI Galway have built a machine that can instantly identify drugs in a mixture of substances. It can even assess the drug's purity.
The device uses a laser and a technique knows as Raman spectroscopy, Dr Ryder explained. The prototype system is too big for portable use, but compact versions could also be produced that could run on a lap-top computer.
It could become an important tool for law enforcement. "Take a concert, for example. If gardai find tablets on someone who says they're aspirin, the Garda can put it through this machine which will show if they are aspirin or if they are, in fact, ecstasy."
In Raman spectroscopy, first observed by an Indian scientist C.V. Raman, in 1928, a laser shines light emitted at a single wavelength at the suspect material, for example, a bag of white powder believed to be cocaine. Some of the light is reflected off, some is absorbed into the material and some is scattered away.
Most of this scattered light has the same wavelength as the original light, but a tiny fraction - Raman scattering - has a different wavelength, because the light loses or gains energy when it interacts with the material. It is this light which is examined by Dr Ryder's device. This light is plotted on a graph called a Raman spectrum, which is unique for every chemical compound. Cocaine, ecstasy, sugar and flour will each have their own graphs, their own molecular fingerprints.
When the laser shines through the bag of suspected cocaine, all the fingerprints of all the different materials in the powder are combined on a composite spectrum, which is analysed to identify each material present.
These data can be compared with a database of fingerprints taken from pure drugs, so all the different substances in the sample under test can be identified. It will show, for example, that the suspect substance contains cocaine, as well as sugar or glucose used to dilute the cocaine.
By putting the composite spectrum of the suspect material through a computer programme, the purity of the cocaine can also be measured. Because the laser can shine through glass and plastic containers, this technique could also reduce the possibility of contamination.
The research to date has focused only on drug analysis, but the device has other applications. It can identify hazardous chemicals in the case of a spillage and also determine the chemical make-up of explosives.
Dr Ryder spoke about his new technique at a conference in London last March titled "Fighting Crime through Technology".