Development of High Volume Portable Aerosol-to-Hydrosol Sampling Technique

Qishuang He and Maosheng Yao*

State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering Peking University, Beijing 100871, China

     Abstract Number: 116
     Last modified: April 15, 2010

Abstract
In this study, an RCS High Flow sampler was adapted to be used with strips filled with mineral oil of 150 or 200 ul for each of its small cubes. Bacillus subtilis and Pseudomonas fluorescens were aerosolized and collected by the RCS High Flow sampler loaded with mineral-oil-strip for 1, 2 and 5 min. In addition, the adapted aerosol-to-hydrosol sampler was also tested when sampling environmental bioaerosols in four different environments (back yard, student dorm, hospital and outdoors). The performances of RCS with mineral oil were compared with use of agar in all experiments. Air samples collected by RCS with mineral oil were cultured and also quantified using qPCR and the results were compared with those obtained by microscope counting.

When sampling B. subtilis aerosols, use of mineral oil was shown to report significantly higher culturable concentrations regardless of the sampling time. In contrast, higher P. fluorescens concentrations were observed for 2 min sampling when mineral oil was used. When sampling in different environments except student dorm, use of mineral oil was observed to yield significantly higher bacterial concentration levels compared to use of agar, about 2-4 times. The results from qPCR tests indicated that the total bacterial concentrations were substantially higher than the culturable ones. The sampling time and mineral oil volume were observed to play a role for the performance of RCS High Flow sampler. When using mineral oil as the collection medium, difficulties of removing oil from the strip and well mixing of bacteria were encountered.

This study demonstrated a high volume (100 L/min) portable aerosol-to-hydrosol sampling technique, and it holds broad promise when coupled with qPCR technology in monitoring airborne biological threats.