文摘
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/cm2 to 1 μg/cm2) both individually and as components of mixtures. Detection of explosives was demonstrated in the presence of an interfering matrix. A large surface (5 cm ×15 cm) on which 1 μg/cm2 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.
