Solid state speciation of elements in urban dust by sequential leaching and total reflection X-Ray fluorescence spectrometry

Abstract

A five-stage sequential leaching procedure was performed for speciation of S, K, Ca, V, Cr, Ni, Cu, Zn, Pb and Sr in ‘Vehicle Exhaust Particulates’ certified reference material (NIES 8) and filter collected urban dust samples. The leaching time of 20 min was applied in each step. The leachates and the solid residues were separated by centrifugation. The element concentrations were determined by total reflection X-ray fluorescence (TXRF) spectrometry in the range of 1 μg g −1 to 5 mg g −1. Ca, Sr and Zn were found mostly in the water soluble fraction, while Cu and Pb in the hydrogen chloride soluble fraction (oxide and carbonate phase). Cr, V and Ni were distributed first of all between the water soluble and the hydrogen chloride soluble fractions in ratios of 30:70, 40:60 and 60:40, respectively. These observations are characteristic for the three samples investigated, independently from their different sampling place and sampling time.