The present invention relates to a method for determining the presence of a mutation in a first sample comprising first polynucleotides. The reference sample comprises reference polynucleotides. The first sample and a reference sample are subjected to electrophoresis in the presence of at least one intercalating dye. During electrophoresis the temperature of the first sample and the reference sample is changed by an amount sufficient to change an electrophoretic mobility of at least one of the first or reference polynucleotides. Fluorescence intensity data are obtained. The fluorescence intensity data are indicative of the presence of the first and reference polynucleotides. The data are processed to determine the presence of mutation in the first polynucleotides.