THE DETERMINATION OF ARSENIC IN REFORMING CATALYSTS BY HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY

The determination of arsenic in reforming catalysts by hydride generat ion atomic absorption spectrometry (HG-AAS) was investigated. Platinum and platinum-rhenium catalysts based on alumina were digested with hy drochloric acid in Teflon vessels of a closed microwave system. The mi xture of potassium iodide and ascorbic acid was added to the solutions to ensure that the analyte was in trivalent form before hydride gener ation. The influence of several metals on the arsenic signal at concen trations up to 10 times higher than expected in catalysts was evaluate d and a significant interference was found only for platinum. However, in the case of highly polluted catalysts, an additional decrease of t he signal is caused by the simultaneous presence of other elements. Th e Standard Addition and Successive Dilution (SASD) method was successf ully applied for calibration purposes. The accuracy of the proposed pr ocedure was confirmed by the determination of arsenic in certified ref erence material CTA-FFA-1 fly ash. The RSD of the analytical procedure was found to be below 10% and the detection limit was calculated to b e 0.2 mu g/g. The procedure is fast and takes less than two hours. As a result of our investigation, the arsenic, being the main factor infl uencing the quality of the reforming catalysts, was determined in the range from below 0.2 mu g/g (non-contaminated catalysts) up to 10.4 mu g/g (highly contaminated catalysts).