The invention relates to a method for the sequence-specific analysis of nucleic acids in a sample in which the nucleic acid is present at least partially as a double strand, which method uses electrochemical detection methods (e.g. with [OsO4(bipy)]). In particular, the methods comprise steps in which the at least partially double-stranded nucleic acid strands are converted by thermal denaturation to single strands which are termed target strands, and at least one nucleic acid strand designated protective strand is added, which protective strand can hybridize with a target strand, in order to form partial double-stranded segments, wherein the protective strands are shorter than the target strands, wherein the temperature of the sample is rapidly lowered to a temperature of below 5° C., preferably below 0° C. The invention also relates to devices which are suitable for these methods comprising a flow system in which the steps of the method can take place consecutively, having heatable sections for thermal de
