A highly sensitive new method of testing explosives was developed by a group of scientists at Aston Labs – the research group of Professor R. Graham Cooks at Purdue University.

Single nanogram amounts of the explosives such as TNT (Trinitrotoluene), RDX (hexogen), HMX(octogen), PETN (penthrite) and their mixtures were detected and identified in a few seconds on the surface of human skin without any sample preparation by mass spectrometry sampling method called desorption electrospray ionization or DESI, a proprietary technology introduced by Dr. R. G. Cooks.

Desorption electrospray ionization (DESI) is carried out by directing electrosprayed charged droplets and ions of solvent onto the surface to be analyzed. The impact of the charged particles on the surface produces gaseous ions of material originally present on the surface that can be analyzed by mass spectrometer.

In this experiment, a solution of methanol and water with addition of sodium chloride was sprayed onto human skin, a hand or a finger. If any of the explosives were present (with exception of TNT) they would form the chloride adducts with sodium chloride that were detected by tandem mass spectrometry. In case of TNT, the radical anions were examined to confirm the identification.

Article citation: Dina R. Justes, Chem. Commun., 2007, DOI: 10.1039/b703655h