Diphenylamine-colorimetric method for DNA assay: a shortened procedure by incubating samples at 50 degrees C.

We describe a modified procedure of the diphenylamine-colorimetric method for assay of DNA that is shorter than the procedure described by Burton. This improvement is achieved by raising the sample incubation temperature to 50 degrees C. The higher temperature hastens and stabilizes the diphenylamine reaction with DNA so that absorbances of samples can be measured as early as 3 h after the reaction is started. This shortened assay is able to detect as little as 3 micrograms of calf thymus DNA. This method is suitable for measuring DNA content of epidermal tissue.