STRAS: a new high-time-resolution aerosol sampler for particle-induced X-ray emission (PIXE) analysis

The joint use of hourly resolution sampling and analyses with accelerated ion beams such as with the particle-induced X-ray emission (PIXE) technique has allowed the measurement of hourly temporal patterns of particulate matter (PM) composition at many sites in different parts of the world. The demand within the scientific community for this type of analysis has been continuously increasing in recent years, but hourly resolution samplers suitable for PIXE analysis have been discontinued and/or suffer from some technical limitations. In this framework, a new hourly sampler, STRAS (Size- and Time-Resolved Aerosol Sampler), was developed for the collection of PM10, PM2.5 or PM1. It allows automatic sequential sampling of up to 168 hourly samples (1 week), and it is mechanically robust, compact and easily transportable. To increase PIXE sensitivity, each sample is concentrated on a small surface area on a polycarbonate membrane. Comparison between the elemental concentrations retrieved by STRAS samples and samples collected using a standard sequential sampler operated in parallel shows very good agreement; indeed, if both the samplers use the same kind of membrane, the concentrations of all detected elements are in agreement within 10 %.