Penicillamine is a medication used to treat Wilson's disease, rheumatoid arthritis, and cystinuria. However, during the manufacturing process, impurities may be introduced into the drug substance. These impurities can affect the safety and efficacy of the medication. Therefore, it is important to monitor and control the levels of impurities in penicillamine to ensure the quality of the drug product. Some of the potential impurities in penicillamine include disulfides, sulfides, and oxidized derivatives.