was located about 4.5 m high above the ground. The loaded filters
were dried at 110 °C overnight. Scanning electron microscopic images
of the loaded filters are shown in Fig. 1. The average mass (±SD) of
dried empty filters used in Istanbul and Budapest changed in the
range of 1.52±0.01 g and 1.46±0.05 g whereas those loaded with
airborne particulate matter varied in the range of 1.63±0.05 g and
1.53±0.04 g, respectively. The loaded filters were cut into small
pieces each weighing approximately 1 mg, and placed onto the platform
for analysis, whereas the CRM was put onto the platform in
powder form after drying at 110 °C. The volume of liquid standards
and modifier solutions pipetted onto the platform was in all cases
10 μL. In order to cover the platform and the graphite tube with Zr
or Ir, 50 μL of standard solution (1000 μg/mL) of Ir or Zr was pipetted
onto the platform and vaporized at 2100 °C. This procedure was
repeated ten times.