Meso-scale VOC-mixture analyzer with tunable separation and microsensor array detection

A novel portable instrument developed for field determinations of complex mixtures of volatile organic compounds (VOCs) is described. The key features of the instrument are a miniature multi-stage adsorbent preconcentrator/focuser, two series-coupled separation columns with pressure,and temperature tunable retention control, and an integrated array of four chemiresistor (CR) sensors coated with Au-thiolate monolayer-protected nanoparticles (MPN). MPN-CR array response patterns are used with retention times to identify eluting vapors. Air is used as the carrier gas. Calibrations of 20 common indoor air contaminants gave LODs in the range of 0.05 ng/g similar to 0.53 ng/g for a 1 L sample volume. Results of preliminary analyses of characteristic VOCs generated from U.S. currency as well as vapor-phase markers of environmental tobacco smoke (ETS) at low- or sub- ng/g levels are presented.