Novel approach for determination of trace metals bound to suspended solids in surface water samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS)

Abstract

An approach for rapid determination of ultra-trace concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in suspended solids present in surface water was developed and validated for three Austrian rivers (Danube, Leitha, Schwechat). Elemental analysis was performed by ICP-SFMS via slurry-type nebulization of non-centrifuged (total elemental concentration) and centrifuged (dissolved elemental concentration) surface water samples. The elemental concentrations in suspended solids (c_ss) were determined, relating the difference of the total elemental concentration and the dissolved elemental concentration to the concentration of suspended solids (gravimetric determination). The quality of the obtained data was evaluated calculating the expanded uncertainty of measurement according to Eurochem/CITAC. The applied analytical procedure yielded values for c_ss associated with low uncertainties for elements with high particle bound fractions (Zn, Pb) and suspended particle concentrations >5 mg L^–1. The novel method provided partition patterns and related partition coefficients (K) which were in agreement with available literature data. The investigated elements could be classified into three groups: (i) elements showing both considerable particle bound fractions (Ni 0%–50%, Cr 22%–33%, Cu 37%–100%) and large fractions of dissolved metals; (ii) elements with a pronounced tendency towards particle binding, such as Pb and Zn, showing particle bound fractions of 56%–100% and 71%–83%; and (iii) elements being predominantly present in the liquid phase (As, Se). The concentrations of Ag and Cd were consistently below the limits of detection for all investigated rivers.