MONITORING INDOOR AMBIENT ATMOSPHERES FOR VOLATILE ORGANIC-COMPOUNDS USING AN ION MOBILITY ANALYZER ARRAY WITH SELECTIVE CHEMICAL-IONIZATION

Three ion mobility analyzers with different reagent gases for chemical ionization were interfaced to a single computer and operated with a s oftware package created for simultaneous and continuous monitoring of 1 to 8 analyzers. Mobility spectra were collected and digitized on sep arate input channels with 200 ms sampling intervals for individual ana lyzers. Volatile organic compounds (VOCs) in indoor ambient, atmospher es were monitored in two scenarios: laboratory air during designed rel eases of several VOCs and ambient air in a central chemistry storeroom used for undergraduate laboratories. The ion mobility analyzer with r eagent ions of H(H2O)(n)(+) (n = 2 - 4) exhibited response toward alco hols, aldehydes, and other VOCs with low proton affinities, However, a nalyzers with reagent ions of elevated proton affinity including aceto ne and dimethylsulfoxide showed selective response toward only VOCs wi th proton affinities greater than that of the reagent ion. Thus, two t iers in selectivity of array response were established through the ion ization chemistry joined with ion mobilities and was demonstrated thro ugh studies of indoor air quality.