Native mass spectrometry (native MS) involves recording mass spectra in solution conditions that mimic the physiological conditions, and with instrumental conditions that perturb the non-covalent interactions as little as possible (electrospray ionization and low-energy collisions in the instrument). When the intermolecular non-covalent assemblies are detected intact, the stoichiometries can be read directly from the detected masses. In nucleic acids, our past work focused mostly on DNA duplexes and G-quadruplexes, where either the number of strands or incorporating specific cations provides a mass signature for the secondary structure formation. However, the cases where intramolecular folding is not accompanied by a mass change are more difficult to assess with mass spectrometry.