The method, an adapted form of desorption electrospray ionisation mass spectrometry, requires minimal sample preparation and relies on commercially available laboratory equipment.

Experts believe that panic over a bird flu epidemic could provoke consumers into buying their own supplies of Tamiflu (oseltamivir phosphate) - an antiviral drug sold by Roche to treat avian flu.

At $6.50 a pill Tamiflu is relatively expensive, so people may look to unauthorised online pharmacies to get a better deal, who could market illegal versions of the drug that contain no active ingredients.

Both the World Health Organization (WHO) and the US Food and Drugs Administration (FDA) have created initiatives to crack down on counterfeit dug production, but limitations in the technology used to screen these drugs could have a serious impact on how effective these programs prove to be.

High performance liquid chromatography, the current technique used to screen real Tamiflu from fakes, takes up to an hour per sample, limiting the number of drugs that could be examined. The DESI-MS method, which has been adapted by researchers from the Georgia Institute of Technology to screen Tamiflu, would take just three minutes.

In addition, the simple set up of the system means the method could be easily employed in hospitals and by drug regulators to ensure that patients receive effective, regulated drugs.

To analyse a sample, the user would simply need to compact the powdered sample into a pellet and place it into the DESI-MS system. The device then sprays a high-power liquid jet at the particle to dislodge and dissolve the sample in a droplet of the liquid. The liquid is a mixture of water and methanol, which dissolve organic compounds, together with chemicals that react with the active ingredient in Tamiflu.

The mass spectrometer would then analyse the droplet of water to find the molecular mass of the substances present in the mixture. A spectral analysis that returned a molecular mass corresponding to the products of the expected chemical reaction would suggest the sample contained the correct antiviral drug. However, if the spectral analysis did not return this result, the substance would be subject to further chemical analysis to validate the suspicions.

It would have been possible simply to perform the mass spectrometry on the sample without this chemical reactions, but according to Facundo Fernandez, one of researchers , this approach allows a more specific screening than would otherwise be possible.

"The advantage is that it's one more layer of selectivity. The sample molecules must be the exact weight, they must be soluble in the liquid, and they must perform the correct reaction," he told LabTechnologist.com. "It's important to include all these safety measures to ensure we're looking at the correct molecule."

Fernandez believes the technique could be applied in the near future. "I would say it's pretty much ready to go," he said. "It could be used by regulatory agencies, hospitals, and local forensic labs very easily."