1. A method for obtaining spectral data, comprising the steps of: (a) mixing a crown ether, cryptand, or macrocyclic polyether with a large molecule so that the crown ether, cryptand, or macrocyclic polyether binds non-covalently to the large molecule to form a large molecule/crown ether, cryptand, or macrocyclic polyether complex; and (b) performing electrospray ionization mass spectrometry to obtain spectral data of the large molecule-crown ether, cryptand, or macrocyclic polyether complex.