Analysis of heavy metal aerosols on filters by laser-induced plasma spectroscopy

Particulate heavy metals can lead to severe toxic and carcinogenic effects in humans when inhaled in higher concentrations. For the development of a quasi-continuous emission monitor based on automatic filter sampling on a filter band, laser-induced plasma spectroscopy (LIPS) was studied for analysis of heavy metal aerosols on quartz fiber filters. The system consists of a 19-inch laser and detector module connected to a miniaturized sensor head through fiber optics, allowing maximum flexibility of the set-up. Parameters for optimum time-resolved analysis, i.e. detection wavelength, timing and filter material, were established. The LIPS investigations were accompanied by a rigorous reference analysis based on total reflection X-ray fluorescence (TXRF) analysis. The detection limits for heavy metals (Cd, Ni, As, Co, Mn, Sb, Cr, Tl, Sn, V, Cu and Pb) on filters varied between 0.01 and approximately 0.91 μg cm^-2, corresponding to volume detection limits of 0.02-2.73 μg m^-3. Analysis of filter samples from waste incineration demonstrated the potential of the LIPS approach. In combination with an echelle spectrometer, ambient samples from environmental monitoring could be characterized in much better detail, due to the improved detection limits and the superior spectral resolution, and spectral range of the echelle.