RNA molecules can be analyzed on both native or denaturing agarose and polyacrylamide gels. Non-denaturing RNA electrophoresis eliminates the need for hazardous chemicals, but due to intramolecular interactions, RNA molecules can form extensive double-stranded structures that are quite difficult to disrupt. As a result, accurate sizing of RNA molecules is not always possible under non-denaturing conditions. Native RNA electrophoresis is therefore typically used to assess the overall quality of total RNA. Denaturing electrophoresis is recommended to precisely determine the size and integrity of RNA molecules.