Chemical speciation of metals and sulphur in air dust by sequential leaching and total reflection X-ray fluorescence analysis

A rapid five-step sequential leaching procedure was developed for speciatio n of S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Ph in the certified refere nce material, NIST (NBS) 1648 Urban Particulate Matter applying centrifugat ion, stepwise tip-filtration or continuous-flow filtration to separate the leachate fractions. The element concentrations were determined by TXRF spec trometry in the range of 80 mu g g(-1) to 50 mg g(-1), investigating 1 to 2 0 mg aerosol samples. The leaching time was reduced to 20 min for each step and a further reduction to 1 min was proved to be sufficient for extractio n of the environmentally available fraction. The exchangable (water soluble ) fraction of Ca, Ni, S, Zn and Cu, K, Mn, V amounted to 50 to 80% and 20 t o 40%, respectively. In hydrochloric acid nearly the total amount of Pb, 70 % of Cu, 30 to 40% of V, Mn, Fe, Ni and Zn were dissolved. A total recovery of 89 to 114% was found for all elements investigated with exception of K, Ti and Cr which gave a deficit from 30 to 70%.