Rainwater analysis: A comparison between proton-induced X-ray emission and graphite furnace atomic absorption spectroscopy

Rainwater was collected and analyzed for trace metals by graphite furnace atomic absorption spectroscopy (GFAAS) and proton-induced x-ray emission (PIXE). For the PIXE analysis, a nonselective preconcentration technique was used to dry the samples onto polystyrene films. Good agreement was found in the concentrations for the elements determined in common (Cu, Fe, Mn, Pb, and Zn), even though the PIXE analysis had some problems with sample contamination. An advantage of the PIXE analysis is that 26 elements can be determined simultaneously. The elements P, S, K, Ca, V, Mn, Fe, Ni, Zn, As, Br, and Pb had concentrations significantly higher than the chemical blank and detection limits and thus could be routinely analyzed by PIXE. The technique is promising for the other elements Ti, Cr, Co, Cu, Ga, Ge, Se, Rb, and Sr because considerable improvements in detection limits can be achieved by lowering the content of the blank and by increasing the analysis time