Mechanistic study of the aluminum interference in the determination of arsenic by electrothermal atomic absorption spectrometry

The interference effect derived from the presence of aluminum in the wall and platform atomization of arsenic using two sampling modes (aerosol vs. liquid drop) was revisited. The mechanistic action of the Al interference seems to be the result of the formation of some gas phase Al oxide, which would absorb at the arsenic analytical wavelength. A vaporization/condensation process for aluminum oxide seems to exist into the graphite tube with temperature. The effect of protons (as nitric acid) and activated carbon on the behavior of the Al interference was tested. A beneficial effect of overcoming the Al interference was derived from the presence of activated carbon. The mechanistic action of both, protons and activated carbon, was also proposed.