title: Detection of explosives as negative ions directly from surfaces using a miniature mass spectrometer.
abstract: A miniature mass spectrometer was modified by incorporating a conversion dynode detector system and the appropriate electronics to allow the detection of negatively charged ions. The system was fitted with a discontinuous atmospheric pressure interface to allow external ionization by desorption electrospray ionization (DESI). It was used to identify the explosives 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenyl-N-methylnitramine (Tetryl), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) present in trace amounts on surfaces (500 pg/cm(2) to 1 microg/cm(2)) both individually and as components of mixtures. Detection of explosives was demonstrated in the presence of an interfering matrix. A large surface (5 cm x15 cm) on which 1 microg/cm(2) samples of TNT, Tetryl, and HMX had been spotted randomly was interrogated in 22 s in the full scan mode, and signals characteristic of each of the explosives were observed in the DESI mass spectrum.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Sanders
authors.forename: Sameer
authors.initials: S
authors.lastname: Kothari
authors.forename: Guangming
authors.initials: G
authors.lastname: Huang
authors.forename: Gary
authors.initials: G
authors.lastname: Salazar
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks