Evaluation of capillary electrophoresis combined with a modified European Community Bureau of Reference (BCR) sequential extraction for determining the distribution of iron, zinc, copper, manganese and cadmium in airborne particulate matter

This work evaluated the potential of a capillary electrophoresis (CE) method to determine the distribution of Fe, Zn, Cu, Mn and Cd in an airborne particulate matter (PM) after a sequential extraction based on the European Community Bureau of Reference (BCR) protocol. The CE experimental conditions were optimized for sensitively measuring trace metals ion the BCR extractants. Limits of detection were at low-mug/l (mug/g) levels and mid-mug/l (tens of mug/g) levels using electrokinetic and pressure injection, respectively. The other focus of this work was to speed up the BCR sequential extraction procedure by using ultrasonication in place of mechanical stirring. The reliability and applicability of the accelerated extraction scheme were evaluated using a Standard Reference Material, NIST 1648 Urban Air PM. The accelerated method had good precision (relative standard deviation typically below 10%) for all metals in all fractions, and the results were reasonably comparable to those obtained using the conventional method. The overall operating time was reduced from 51 hours (conventional method) to 2 hours (ultrasound-accelerated method). The studied analytical methodology was also applied to some actual filter-collected PM2.5 samples from two source types: urban ambient air and a highway tunnel (the latter representing an anthropogenic-rich source as vehicle emissions). Conclusions were drawn about the metals themselves, and, in general, the metal distributions between the two source types were similar, indicating that the urban air is characteristic of an anthropogenic-rich PM.