Sample collection and preparation for analysis of airborne particulate matter by total reflection X-ray fluorescence spectrometry

The steady interest in clarifying the relevance of atmospheric particles for health risks requires fast and easy to handle methods for the collection and characterization of airborne particulate matter. For the present study, airborne dust was collected by filtration as well as by impaction with a six stage Berner type impactor. Filtration was performed with cellulose nitrate filters, and in the Berner type impactor a thin spray film was employed as collection medium. The exposed portions of both materials were punched out and digested. Three different digestion techniques were studied and intercompared: open digestion (OD) with nitric acid and hydrogen peroxide, high pressure acid digestion (HPA), and cool plasma ashing (CPA). Decomposition by CPA showed highest reliability and practicability for these materials. After digestion of the samples, the residues were dissolved with nitric and hydrochloric acid, mixed with an internal standard element and analyzed by Total Reflection X-Ray Fluorescence Spectrometry (TXRF). Due to the high detection power of TXRF, the sampling time could be reduced to less than 1 h. By this means it was possible to collect and analyze several samples successively during one day. A diurnal variation was established with both sampling systems in parallel.