The dimercaptosuccinic acid (DMSA) stability at pH = 3.8, 7.1, 8.8 and the interaction with SnCl2·2H2O were investigated. The degradation of DMSA is the most significant at alkali pH. There where observed oxidized and dimerized
forms of DMSA and fumaric acid presence. Progress of instability is less substantial and slower under neutral reaction conditions.
At acidic pH the concentration of soluble DMSA decreases with the time. The ligand forms with SnCl2 complex under alkali pH = 8.8 and its chemical formula was determined as Sn(DMSA)2.