Determination of Impurity Elements in High Purity Graphite by ICP-MS after Mixture Acid Digestion in Reflux Condenser System

The method of determination of 35 trace impurity elements in high purity graphite was established. Samples were digested by the mixture of 1 mL HNO₃，1 mL HClO₄ and 3 mL H₂SO₄ at 220 ℃ in reflux condenser system. Sc, Rh, Re and Cs were utilized as internal standards to correct the signal drift. The detection limit of various elements is from 0.000 6 μg•L^-1 to 0.1 μg•L^-1, the recovery rates are between 82% and 110%, the RSD(n=10) is in the range of 0.58% and 5.8%. The method is suitable for the determination of impurity elements in high purity graphite.