Due to the highly charged nature of DNA and RNA, the electrostatic association between ions and nucleic acids predominantly influences the structure and function of the nucleic acid molecules. This project is an experimental technique that can quantitatively and fully dissect the molecular constituents of the ion atmosphere associated with nucleic acids. In this project, buffer equilibration is combined with atomic emission spectroscopy (BE-AES) to read out the number of different monovalent and divalent cations associated with a nucleic acid and to quantitate the relative affinity of the cations. Results establish an unprecedented standard for ion association with nucleic acids and allow rigorous examinations of the widely used Nolinear Poisson-Boltzmann(NLPB) electrostatic theory and other theories (see also ISIM project).