Determination of hexavalent, trivalent and metallic chromium in welding fumes

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Abstract
A procedure for the quantitative determination of the different chemical compounds of chromium in welding fumes is presented. Cr(0), Cr(III) and Cr(VI), whose toxicological properties are very different, are the three oxidation states in which this element can be present in air. The speciation has been performed by a selective solubilization procedure of welding fume particulates, collected on proper filters. Cr(VI), Cr(III), and Cr(0) are selectively and separately determined; it is also possible to distinguish the water soluble Cr(III) from the insoluble. Chromium in the examined welding fumes is present in all the three oxidation states (hexavalent, trivalent and metallic). Among the Cr(III) compounds the largest fraction in the welding fumes is represented by the soluble species. The importance of the kind of filter chosen to sample the particulate is illustrated, as well the typical interferences that can be encountered either in the solubilization or in the analytical measurements. Reprodiicibility obtained analysing 12 samples of welding fumes collected in the same working conditions was good and the standard deviation was 5%.