An Investigation into the Effects of Bioscreening Tests on DNA Quantitation and DNA Profiling of Samples

Abstract

Bioscreening tests are used to screen items and surfaces at crime scenes and can provide an indication of whether any body fluids are present. The Combur3 Test® E, Luminol, Leuco Crystal Violet, Phadebas®, and Acid Phosphatase tests were evaluated to see if they had any effect on the DNA quantitation and DNA profiling of samples. This was achieved through comparison of data from treated and untreated samples on different substrates at different time intervals. The Combur3 Test® E had no significant effect on DNA quantitation and profiling results. For samples treated with the LCV test, DNA quantitation values were significantly reduced when compared to untreated samples, and partial or no profiles of DNA were obtained. The effect was thought to be due to possible inhibition from the fixative in the LCV solution. For samples treated with the Luminol test, quantitation values were significantly reduced when compared to untreated samples and only one sample produced a partial profile. The effect on DNA profiling was thought to be due to the dilution of blood used and chemicals in the Luminol solution. The Phadebas® test had no effect on DNA quantitation results, however significantly lower average peak heights were generated from treated samples. Variance in the amount of extracted DNA added into the amplification reaction could have accounted for this difference in peak heights. For samples treated directly with the Acid Phosphatase test, quantitation values were significantly increased and average peak heights significantly decreased (though full profiles were still generated) when compared to untreated samples. Overestimated quantitation results may have subsequently affected the peak heights causing these significant effects with the direct Acid Phosphatase testing. The indirect Acid Phosphatase testing had no significant effect on DNA quantitation and profiling results. Differences with DNA quantitation and profiling results were seen between substrates, however no correlation was seen between substrate type and the effect of treatment on results generated. No correlation was also seen between the DNA quantitation and profiling results and the effect of treatment as the time between testing and sampling increased.