A new cascade impactor for aerosol sampling with subsequent PIXE analysis


A small deposit area low pressure impactor (abbreviated to SDI) has been developed and tested. The device has been designed specifically to collect size-fractionated aerosol samples in remote locations for subsequent chemical analysis by PIXE. The SDI is a 12-stage, multinozzle device, but the deposit for each stage remains confined to an area with diameter less than 8 mm. It operates at a flow rate of 11 L/min and accepts the same, 25 mm diameter substrate rings as the PIXE International cascade impactor. The experimental cut-points for stages 12 through 1 are 8.50, 4.08, 2.68, 1.66, 1.06, 0.796, 0.591, 0.343, 0.231, 0.153, 0.086 and 0.045 μm equivalent aerodynamic diameter. The SDI has been tested in (and employed for) size-fractionated aerosol sampling in the Finnish Arctic and at Summit in Greenland. The data show that the SDI gives results very similar to those obtained with the PIXE International impactor, but with detection limits that are much lower. This suggests that the SDI can be used with shorter sampling times or in areas where concentrations are smaller to obtain reliable size distribution data. The results also suggest that data for a greater number of elements can be obtained with the SDI.