2.3. Field sample treatment
Prior to the field tests, each filter and microcentrifuge tube was autoclaved at 121 °C and 17.6 psi.
Each autoclaved filter was placed into an alcohol-sterilized and cleaned filter holder.
The samplers were wrapped in sterile aluminum foil and put in an icebox during transportation.
The sample flow rate of 3.5 L/min for the sampling line was calibrated prior to sample collection using a dry calibrator (Defender 510- H, Bios International Co., USA).
Immediately after sampling, the filter was charge neutralized and transferred from a filter holder to a sterile 15 mL tube in a clean area.
The sample transportation and the preparation of field and transportation blanks followed procedures described by Lee et al. (2006).