Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry

cited By 27International audienceA European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the 52Cr+ and 53Cr+ isotopes. If there was strong interference with m/z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/z 53 if digestions were performed with HNO 3+H2O2. This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH4+/NH3 buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform. © Springer-Verlag 2003

Chromium speciation by hyphenation of high-performance liquid chromatography to inductively coupled plasma-mass spectrometry - Study of the influence of interfering ions

cited By 55International audienceThis study presents the development of a speciation method for chromium redox species by HPLC-ICPMS. Chromatographic separation is performed with CG5A-CS5A columns set (Dionex) containing both anionic and cationic groups to retain Cr(VI) and Cr(III), respectively, associated with a nitric acid elution. After optimisation, detection limits lower than 0.5 μg L -1 were obtained for both Cr species. This method is free from interferences possibly linked to chloride and organic or inorganic carbon on the two most abundant chromium isotopes ( 52Cr + and 53Cr +). A modification of the chemistry of Cr(III) was, however, observed in the presence of hydrogencarbonate ions. In this medium, for trivalent chromium, three peaks instead of one arc present on the chromatograms. This modification was attributed to the hydrolysis of Cr(III) that occurs at these pH values. The accuracy of the analytical procedure was verified by analysing a certified reference material (BCR-CRM 544) and spiked natural waters. The concentrations found for Cr(VI) were in good agreement with the certified and spiked values. Because of the high reactivity of Cr(III) in alkaline medium, recoveries were not completely quantitative. © The Royal Society of Chemistry 2003