Oct 11 2007
A laser that can detect counterfeit drugs through packaging has been developed by British scientists, allowing investigators to check on their authenticity without opening sealed bottles or packs.
Trials of the technique have proved in principle that the laser can tell real antimalarial medicines from fakes, suggesting that it could play a major role in controlling one of the world's most significant counterfeiting rackets. Between 50 and 90 per cent of malaria medicines sold in some African countries are thought to be fake, and account for up to 20 per cent of deaths from the disease.
The new imaging technique can pick up the characteristic light signature of pharmaceuticals' active chemical ingredients through glass, plastic and cardboard. The laser system, which will be developed as a desktop or hand-held device, could also be used to monitor the growing problem of fake "lifestyle drugs", such as Viagra.
And it can detect liquid explosives through plastic containers and glass bottles, raising the prospect that it could be used in airport security. However the laser eye cannot yet see through metal. Details of the method have been published in the journal Analytical Chemistry.
It was already possible to detect counterfeit drugs and explosives with lasers using a method known as Raman spectroscopy, but this works best when tablets or liquid preparations have been removed from their packaging. This makes it difficult for genuine drugs to be sold if they pass the test. A team led by Pavel Matousek, of the Central Laser Facility at the Rutherford Appleton Laboratory in Oxfordshire, has now developed a variation. The group also includes scientists from the University of Oxford and Imperial College, London.
"Drug counterfeiting is a major problem worldwide, and in many cases we are talking about drugs where people die if they do not get the genuine article ¡V diseases like malaria, tuberculosis, cancer," Dr Matousek said.
In Raman spectroscopy, photons bounce off individual molecules, imparting them with energy. Different molecules produce characteristic "signatures" in the patterns of light that scatter back. However these are drowned out by the immense number of photons reflected by cardboard, plastic or glass packaging.
The new system, spatially offset Raman spectroscopy, collects reflected photons from a point slightly removed from where the laser hits the target. Photons are still reflected from the target's inside layers, but their signal is no longer overwhelmed.