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)

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.