The determination of low concentrations of the platinum-group elements (PGEs) in geological materials is of considerable importance and has attracted numerous studies using inductively coupled plasma mass spectrometry (ICP-MS) combined with a variety of preconcentration techniques. Among these techniques, the Ni-sulfide fire assay has proven the most convenient and efficient. However, Cu and Ni are also collected during the fire assay and cause serious isobaric interference by Cu- and Ni-argides with the light PGEs (Ru, Rh, and Pd). This problem is most pronounced in the analyses of sulfide-rich materials. Here, we report a new technique that involves a combination of standard addition with external and internal calibrations to make corrections for Cu- and Ni-argide interference. This study demonstrates that ICP-MS is suitable for the determination of the PGEs in sulfide-rich geological materials.