Effective sampling duration in determining PAHs and NPAHs concentration in PM2.5 and PM10 glass filters
Egide Kalisa1, Edward Nagato2, Stephen, DJ Archer1, Kevin C Lee1, Stephen B Pointing1, 2, Kazuichi Hayakawa2, Donnabella C Lacap-Bugler1
1Institute for Applied Ecology New Zealand, School of Science, Auckland University of Technology, Auckland, New Zealand, Private Bag 92006, Auckland 1142, New Zealand.
2Institute of Natural and Environmental Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920–1192, Japan
Previous studies have shown significant differences in particulate matter (PM) sampling and filter extraction efficiency between techniques used for chemical composition of the extracted PM. Consequently, data from various study are often difficult to compare due to the differences in experimental design, sampling duration and extraction methods. It remains technically challenging, partly owing to the limited mass of collectable atmospheric PM and its chemical contents. Additionally, little is known about how filter area size influences the extraction efficiency for PAH/NPAHs. The current study was conducted to investigate the effect of sampling duration and extraction efficiency of different filter area sizes on the concentrations of PAHs and NPAHs that can be detected using HPLC with fluorescence and Chemiluminescence detection. Samples of particulate matter less than 2.5 in diameter (PM2.5) and particles less than 10 μm in diameter (PM10) were collected with a high volume air sampler using three sampling periods: seven days, five days and twenty–four hours. PM2.5 filters were cut into different sizes of the original filter, as were PM10 filters. The concentration of PAHs and NPAHs decreased as the duration of the sampling time increased (24 hours > 5 days ≈7 days). The analysis also revealed that the concentration of PAHs and NPAHs was relatively the same sampling duration of five and seven days. In contrast, the sampling duration of 24 hours showed that the particulates are not uniformly distributed over the filter, thus, required a larger sampling area (at least half of the whole filter) for extraction. The shorter collection period does not appear to come at the cost of PAH/NPAH concentrations and therefore may allow for several consecutive sample monitoring.