Mannitol impurities refer to any unwanted substances present in a mannitol sample that may affect its purity, quality, and safety. These impurities may arise from the manufacturing process or from external sources. Common examples include residual solvents, heavy metals, and organic residues. The presence of such impurities can also affect the efficacy of mannitol in pharmaceuticals and other applications. Therefore, it is essential to identify and control these impurities to ensure the quality and safety of mannitol products.