Effect of presumptive tests reagents on human blood confirmatory tests and DNA analysis using real time polymerase chain reaction

Bloodstains often constitute the major physical evidence in crime investigation. Diluted blood invisible to the naked eye can be detected through presumptive tests however such tests can damage samples and prevent further processing such as DNA analysis. In this study, we compared the effects of luminol (prepared according to Weber [15]), Luminol 16®, Bluestar® and benzidine for inhibition in the human antiglobulin test and the human hemoglobin immunochromatographic test and on the total human DNA concentration up to 120 days after sample treatment. Treatment with both luminol solutions and Bluestar® still allowed positive results for the immunologic tests, indicating non-interference with human blood confirmatory tests. However, samples treated with benzidine could not be further analyzed by serological tests. Also, DNA quantification showed that 48 h after benzidine treatment, but not luminol or Bluestar solution application, sample DNA was degraded. Luminol 16® caused DNA degradation already at 30 days post-application. At 120 days post treatment, all samples treated with any of the agents but not untreated samples had DNA degradation.