Novel matrix modifier for direct determination of palladium in gold alloy by electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

The determination of palladium in gold alloy by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) is difficult because of the presence of the gold matrix and the formation of Au–Pd intermetallic complexes. A new matrix modifier for removing the gold matrix was investigated followed by direct determination of Pd by ETV-ICP-MS using an aqueous standard. In the present study, different halides, such as KI, KIO3 and KCl, were evaluated for the removal of the gold matrix by formation of low boiling point auric halide complexes. The influence of the temperature program on the separation efficiency was also studied in this work. A novel pre-reaction step was developed to improve the removal efficiency by enhancing the reaction between auric ions and halides. Under optimized conditions, about 75% of 0.2 µg of gold matrix can be removed and a satisfactory analytical signal can be obtained. The precision of this method was approximately 6% with the use of KI as matrix modifier, and the accuracy was confirmed by the good agreement between the data obtained by the proposed method and those by a wet chemical technique. The detection limits obtained using the proposed method were as low as 0.1 µg g−1, making the method suitable for the determination of Pd in gold alloy.