US researchers have developed a quick and sensitive method that could soon be used at airports around the world for detecting peroxide explosives on ordinary surfaces.

Triacetone triperoxide (TATP) has been used in terrorist attacks, such as the London bombings in July 2005. It is cheap, easy to make and invisible to most conventional explosive detection devices including those routinely used at airports.

Graham Cooks and colleagues at Purdue University, US, used their desorption electrospray ionization (DESI) technique to detect trace amounts of TATP on paper, metal and brick, and in complex matrices such as methanol, vinegar, and diesel. No sample preparation is required, it gives low nanogram detection limits and it takes less than five seconds to obtain spectra.

DESI works by directing a pneumatically-assisted electrospray (cloud of tiny, highly charged droplets) onto a surface. The charged microdroplets interact with analyte molecules on the surface, generating secondary ions that are collected and analysed.

Cooks and his team are now building a portable mass spectrometer that will allow the detection of TATP to be carried out in situ. They hope to make the technology available for use at airports around the world. 'The time scale for wide availability depends on commercial rather than scientific factors,' said Cooks.

Nicola Nugent