DETERMINATION OF MERCURY BY FURNACE ATOMIC NONTHERMAL EXCITATION SPECTROMETRY

The determination of Hg using different variants of the Furnace Atomic Nonthermal Excitation Spectrometry (FANES) is described. In the direct analysis of microvolumes of solutions, the results could be improved by working with chemical modifiers for the stabilization of Hg during the thermal pretreatment. The best results were obtained using Ir and Pd as modifiers, with absolute detection limits of 4 and 12 pg, respectively. The determination of mercury in sample volumes up to 10 ml could be achieved by coupling a cold vapour generation system and an amalgam attachment to the FANES source. A detection limit of 22 ng/l was obtained with this technique. The best results were obtained by using the cold vapour generation technique and in situ enrichment of Hg onto the modified inner surface of the graphite tube of the FANES source. Using Ir for permanent impregnation of the tube a detection limit of 0.0009 mu g/l was found. The influence of hydride forming elements on the determination of mercury by the technique of vapour generation and in situ enrichment was studied. A reduction of the concentration of NaBH4 to 0.002% m/v made it possible to determine traces of mercury in presence of a high excess of hydride forming elements without any depression of the Hg emission intensity. The results were validated using standard reference materials.