The simultaneous interference effects of sodium chloride and magnesium chloride on the atomization of manganese in a graphite furnace were investigated. For this purpose, the individual interference mechanisms of each salt were also studied. It was found that the interference of sodium chloride originates from expulsion of the analyte with matrix and gas phase reaction between manganese and chlorine during the atomization step. In the presence of magnesium chloride, interferences depend on the pyrolysis temperature. If low pyrolysis temperatures are applied, expulsion and gas phase reaction in the atomization step are very likely. At elevated temperatures, MgCl2 is converted to MgO, which does not cause expulsion or gas phase reaction in the atomization step, although some loss of manganese occurs owing to the volatilization of manganese chloride formed in the pyrolysis step. If sodium chloride and magnesium chloride are present simultaneously, interferences are reduced at elevated pyrolysis temperatures. Obviously, the magnesium oxide generated by the hydrolysis of magnesium chloride acts as a modifier and partially protects the analyte, but some losses cannot be completely eliminated because of the interference due to sodium chloride and the volatilization of manganese chloride. (C) 1997 Elsevier Science B.V.