The estimation of DNA contamination in RNA and enzyme preparations

Commercially available RNA and enzyme preparations are monitored for DNA contamination. The method used involves reaction with p-nitrophenylhydrazine and separation of the reaction products by thin-layer chromatography. When this technique is used, RNA preparations and bovine pancreas ribonuclease are shown to have low levels of DNA contamination. An independent method, based on the enhanced fluorescence of DAPI in the presence of DNA, also detected DNA in the RNA preparations but not in the ribonuclease.