Detection of gram-negative Erwinia herbicola outdoor aerosols with pyrolysis–gas chromatography/ion-mobility spectrometry

Aerosol particulate species of the gram-negative bacterium Erwinia herbicola (EH) were detected by stand-alone, analytical instrumentation in an outdoor western United States desert test site. The device consisted of an aerosol collector interfaced to a quartz-tube pyrolysis–gas chromatography/ion-mobility spectrometer (Py-GC/IMS). The detector is about the size of a shoebox, that is, 12 × 9 × 6 in. Bacterial aerosols and background particulates in the 2 to 10 μm-diameter range were collected by a 1000-l/min aerosol concentrator and deposited onto a filter in a quartz tube. Rapid heating to 350 °C in 5 s effected vaporization, and a portion of the pyrolyzate was directed into a GC column. The eluate was detected by the atmospheric-pressure–based IMS. A distinct peak in the GC/IMS data window was used to signal the presence of the EH bacterial aerosol. The sensitivity of this method was relatively good in that values down to five EH-containing aerosol particles per liter of air could be detected in approximately 2.5 min. © 2000 John Wiley & Sons, Inc. Field Analyt Chem Technol 4: 111–126, 2000