Microplasma detection of hazardous compounds

Plasmas have a long-standing analytical history but generally as large, stand-alone laboratory scale instruments. In contrast the physical scaling of microplasmas permit atmospheric pressure operation and battery scale power requirements, thereby permitting mobile field analysis. The energetic species in an otherwise "cold" i.e. nonthermal plasma both dissociates species of interest and excites the elemental constituents. The atomic emission spectrum serves to identify the compound and ideally its molecular composition with intensity corresponding to concentration. For some operational regimes and species, emission from OH*, CH* and often C2* diatomic radicals is produced. Spectral simulation extracts the plasma temperature while the emission further aids compound detection and identification. This is particularly true for compounds such as acetone, ethanol, heptane, toluene, and nitrobenzene. Limits of detection extend to ppb levels for some species such as nitrobenzene. Results will be shown for differentiation of classes of organic compounds such as alkanes, aromatics and oxygenates.