Benzonitrile is a commonly used chemical intermediate in the production of various organic compounds. However, during its synthesis or storage, impurities can be introduced which may affect the quality and purity of the final product. Some common impurities found in Benzonitrile include water, aldehydes, ketones, acids, and other organic compounds. These impurities can be harmful and must be carefully monitored and controlled to ensure the quality and safety of the end product.