<p>Chemical stability of adsorbents in nitric acid is essential for the separation of platinum group metals from high-level liquid waste using extraction chromatography. Through batch adsorption experiments, this study investigated the adsorption performance of two sulfur-containing functionalized silica-based adsorbents, AESE-Si, and Thiourea-Si, and evaluated the chemical stability of six sulfur-containing adsorbents based on sulfur leakage under various nitric acid concentrations, contact times, and temperatures as with other adsorbents. Both adsorbents exhibited high adsorption affinity for Pd(II), while the adsorption of Ru(III) and Rh(III) was affected by nitric acid concentration and temperature. Results indicate that sulfide and thiol functions possess excellent chemical stability in nitric acid media.</p>