Mass spectrometry technique developed for quick on-the-spot analysis

Chemists in the US are developing a mobile mass spectrometer to detect traces of explosives quickly and on-the-spot.

Graham Cooks and colleagues at Purdue University, US, are using desorption electrospray ionisation (DESI) mass spectrometry in their attempts to streamline airport security. In their method, the object under scrutiny is sprayed with a mist of alcohol and water. Molecules from the object's surface are picked up and carried to the mass spectrometer as the mist bounces off the object. The mass spectrometric measurement then takes three seconds, and analysis a further three seconds, so that any explosive material can be quickly spotted.

This technique tackles common problems with detecting explosives, where samples have to be taken away to be analysed. The DESI method can be used on all kinds of surfaces, is very sensitive and doesn't need a vacuum. Plans to make a hand-held analyser are under way, according to Cooks.

'A very large step has been taken in solving the scientific problems associated with specific detection of low levels of explosives with high certainty in short times and without complex sampling procedures,' says Cooks.

He adds that DESI was not originally intended for any particular application, but 'the fact that the method works for a large variety of surfaces is indeed fortunate. We were lucky perhaps to make the appropriate observations but they were made in conjunction with an interest in removing the limitations imposed by vacuum systems on mass spectrometry'.

Katharine Sanderson