Field detection and identification of a bioaerosol suite by pyrolysis-gas chromatography-ion mobility spectrometry

Improvements were made to a pyrolysis-gas chromatography-ion mobility spect rometry (Py-GC-IMS) stand-alone biodetector to provide more pyrolyzate comp ound information to the IMS detector module. Air carrier gas flowing contin uously through the pyrolysis tube, the rate of air flow, and pyrolysis rate were found to improve the relative quality and quantity of pyrolyzate comp ounds detected by the IMS detector compared to earlier work. These improvem ents allowed a greater degree of confidence in the correlation of biologica l aerosols obtained in outdoor testing scenarios to a standard GC-IMS biolo gical aerosol dataset. The airflow improvement allowed more biomarker compo unds to be observed in the GC-IMS data domain for aerosols of gram-negative Erwinia herbicola (EH) and ovalbumin protein as compared to previous studi es. Minimal differences were observed for gram-positive spores of Bacillus subtilis var. globigii (BG) from that of earlier work. Prior outdoor aeroso l challenges dealt with the detection of one organism, either EH or BG. Bio logical aerosols were disseminated in a Western Canadian prairie and the Py -GC-IMS was tested for its ability to detect the biological aerosols. The c urrent series of outdoor trials consisted of three different biological aer osol challenges. Forty-two trials were conducted and a simple area calculat ion of the GC-IMS data domain biomarker peaks correlated with the correct b ioaerosol challenge in 30 trials (71%). In another 7 trials, the status of an aerosol was determined to be bio. logical in origin. Two additional tria ls had no discernible, unambiguous GC-IMS biological response, because they were blank water sprays. Reproducible limits of detection were at a concen tration of less than 0.5 bacterial analyte-containing particle per liter of air. In order to realize this low concentration, an aerosol concentrator w as used to concentrate 2000 1 of air in 2.2 min. Previous outdoor aerosol t rials have shown the Py-GC-IMS device to be a credible detector with respec t to determining the presence of a biological aerosol. The current series o f outdoor trials has provided a platform to show that the Py-GC-IMS can pro vide information more specific than a biological or non-biological analysis to an aerosol when the time of dissemination is unknown to the operator. T he Py-GC-IMS is shown to be able to discriminate between aerosols of a gram -positive spore (BG), a gram-negative bacterium (EH), and a protein (ovalbu min). (C) 2001 John Wiley & Sons, Inc.