Displaying 3 results of Cinchonine Impurities Cinchonine is a natural alkaloid found in the bark of the Cinchona tree. However, it is not always found in its pure form and may contain impurities. These impurities may be other alkaloids like quinine, cinchonidine or cinchonine diastereoisomers. As such, it is important to identify and quantify these impurities for pharmacological and therapeutic applications.