A method is described enabling to eliminate the spectral interference from alumina matrix onto As determination at the wavelength 189 nm by electrothermal atomic absorption spectrometry with deuterium background correction. Matrix modification was performed by the addition of ammonium fluoride to protect the formation of aluminium oxide implicated in causing spectral interference and to increase volatility of alumina matrix via the formation of AlF(3). Pre-treating of the pyrolytic graphite platform with a solution of rhodium and citric acid has enabled to stabilize the analyte up to temperature of 1300 degrees C at which most of AlF(3) could be removed from the graphite furnace. The application of 2 microg of Rh+20 microg of citric acid+200 microg of NH(4)F has enabled an accurate and interference-free determination of As up to 40 microg of Al in the form of AlCl(3) as verified by analytical recoveries study and resulted in characteristic mass and LOD value in the original sample 15 pg and 50 ngg(-1), respectively (10-microL aliquots of sample).