DETERMINATION OF HEXAVALENT, TRIVALENT AND METALLIC CHROMIUM IN WELDING FUMES

A procedure for the quantitative determination of the different chemic al compounds of chromium in welding fumes is presented. Cr(O), Cr(III) and Cr(VI), whose toxicological properties are very different, are th e three oxidation states in which this element can be present in air. The speciation has been performed by a selective solubilization proced ure of welding fume particulates, collected on proper filters. Cr(VI), Cr(III), and Cr(O) are selectively and separately determined; it is a lso possible to distinguish the water soluble Cr(III) from the insolub le. Chromium in the examined welding fumes is present in all the three oxidation states (hexavalent, trivalent and metallic). Among the Cr(I II) compounds the largest fraction in the welding fumes is represented by the soluble species. The importance of the kind of filter chosen t o sample the particulate is illustrated, as well the typical interfere nces that can be encountered either in the solubilization or in the an alytical measurements. Reproducibility obtained analysing 12 samples o f welding fumes collected in the same working conditions was good and the standard deviation was 5%.