Mechanism of action of the palladium and magnesium modifiers in various sample dissolving media in the graphite furnace atomic absorption spectrometry

The effect of palladium and magnesium modifiers on the analytical signals o f seven elements atomized in the graphite tube on the pyrolitic platform wa s investigated. The effect of such sample dilution media as nitric, hydroch loric and perchloric acids and their mixtures was also tested. The mechanis m of modi ner action in relation to various groups of the tested elements h as been discussed on the basis of the obtained results. It was found that t he mixture of palladium and magnesium nitrate always has the same modifying properties as that component which is more active when the components of t he mixture are used individually. Palladium appears to be a good modifier f or all tested elements but. only when the sample was dissolved in nitric ac id. in hydrochloric and perchloric acids rind in the mixed solution of thes e acids with nitric acid palladium loses its properties and in most cases i t becomes a strong interferent causing losses of an analyte. Magnesium nitr ate is a very good modifier but only for non-metal elements. Unlike palladi um, it is also active in the solutions Of all tested acids and their mixtur es. It protects these elements against its losses in the form of volatile c ompounds already during the evaporation and drying of samples as well durin g the pyrolysis stage. Therefore, magnesium should be considered as a modif ier superior to palladium for the non-metal elements.