Entacapone is a medication used in the treatment of Parkinson's disease. Entacapone impurities refer to substances that are present in entacapone medication that are not intended to be there. These impurities can potentially affect the efficacy and safety of the medication. It is important for pharmaceutical companies to monitor and control these impurities to ensure the quality of the medication. Analytical methods are often used to detect and quantify the impurities in entacapone.