The present invention relates to methods and systems for the analysis of the dissociation behavior of nucleic acids and the identification of nucleic acids. In one aspect, methods and systems are disclosed for identifying a nucleic acid in a sample including an unknown nucleic acid and for detecting a single nucleotide polymorphism in a nucleic acid in a sample. In another aspect, methods and systems are disclosed for identification of a nucleic acid in a biological sample including at least one unknown nucleic acid by fitting denaturation data including measurements of a quantifiable physical change of the sample at a plurality of independent sample property points to a function to determine an intrinsic physical value and to obtain an estimated physical change function, and identifying the nucleic acid in the biological sample by comparing the intrinsic physical value for at least one unknown nucleic acid to an intrinsic physical value for a known nucleic acid.