Comparison of spectrometric and autophotographic methods for determining DNA concentrations

Earlier studies from this laboratory demonstrated that a lumigenic detection method could utilize liquid scintillation counters for quantitation of DNA. Advantages included: 1) elimination of the need for radioactive probes, 2) rapid localization of spots by exposure of X-ray film and 3) longer shelf life of probe DNA. A major disadvantage of cutting spots from the membrane for luminometric assay is the destruction (or consumption) of the membrane; another disadvantage is the length of time spent handling the membrane while trying to cut out individual spots. When transmittance was compared with counts per minute for target CAT DNA, both methods gave statistically significant differences between 10 and 100 picograms of target DNA but less than 10 picograms were not significantly distinguished by either method. The digitized x-ray films read by image analysis allowed reliable determination of target DNA concentrations and leaves the original membrane intact to serve as a permanent record of experiments.