Proposed mechanism for the action of palladium and nickel modifiers in electrothermal atomic absorption spectrometry

Abstract

By the use of Fourier transform infrared spectrometry it was found that palladium chloride decreased the temperature of the reduction of PbO and Ga₂O₃ with graphite; nickel chloride only catalysed the reduction of Ga₂O₃. A hypothesis is proposed that nickel and palladium salts promote the reduction of compounds (in atomic absorption measurements) at relatively low ashing temperatures. The resultant free elements form intermetallic compounds or solid solutions with metallic Pd and Ni, thus reducing or almost eliminating loss of analyte due to sublimation of halides, oxides, dimers and other compounds. The high efficiency and universal action of Pd modifiers are because the Pd metal can be easily formed from its compounds and also by the unique catalytic properties of metallic Pd.