2.2. Sample collection and preparation for analytical procedure
Before sampling, the quartz fiber filters (filter diameter: 150 mm)
were heated in laboratory oven at 550 °C for 8 h, in order to remove
organic contaminants. The PM2.5 fractions of urban airborne particulate
matter were monthly collected from June 2010 to May 2011: for
96 h in 4 consecutive workdays [11,12]. The samplers were installed
about 10–15 m away from one of the main roads of the city centers
(GPS coordinates of the sampling sites are: latitude 41°6.5′ N, longitude
29°1.7′ E in Istanbul, and latitude 47°30.6′ N, longitude 19°1.8′
E in Budapest), where traffic approximately 3800 and 3300 vehicles
per hour in Istanbul and Budapest, respectively. The head of sampler