Displaying 11 results of Guanine Impurities Guanine is a naturally occurring organic compound found in DNA and RNA. However, during the manufacturing process of pharmaceuticals, guanine impurities can be introduced. These impurities may affect the efficacy and safety of the drug, and therefore need to be monitored and controlled. Techniques such as HPLC and GC-MS can be used to detect and quantify guanine impurities in pharmaceuticals.