Energy-dispersive X-ray fluorescence spectrometer with capillary optics for the chemical analysis of atmospheric aerosols with high time resolution

Abstract

A new method is presented for the chemical analysis with high time resolution of atmospheric aerosols deposited on a filter surface. The aerosols are collected with a special streaker sampler. This device draws the air by a 8 × 1 mm rectangular orifice through a Nuclepore polycarbonate membrane filter. The filter is mounted on a circular frame, which rotates at 1 revolution per week. The particulate matter is deposited as a 8 mm wide ring. The deposit on the filter is analysed in 1 mm steps, each corresponding to 1 h of exposure. Analysis of the filters is performed using an energy-dispersive X-ray fluorescence (EDXRF) spectrometer comprising an X-ray tube with Mo or Cr anode, a glass capillary with inner diameter of 1 mm, a sample holder with a rotational stage and a Si (Li) semiconductor detection system. The detection limits in capillary optics EDXRF of streaker samples are compared with those obtainable in particle-induced X-ray emission (PIXE) and with atmospheric particulate levels observed in urban areas. The potential of the method of aerosol studies in urban and polluted environments is illustrated by the analysis of samples collected at two sites in the city of Cracow.