Previous studies reported in the literature demonstrate that a range of sampling vehicles can be used effectively for forensic analysis of human DNA in direct amplification reactions. In this study we compared Copan microFLOQ ® swabs with a range of alternative sampling vehicles, using touch DNA samples donated by 15 different volunteers. MicroFLOQ swabs performed well, as did 3 mm diameter discs punched from analytical filter paper. The 3 mm discs could be used in a 5 µl PCR volume, increasing sensitivity, and reducing costs when compared with other methods that require a larger PCR volume. Other inert sampling vehicles, such as interdental toothbrushes and toothpicks also gave good results in direct amplification. The study found a large variation in results between the 15 touch DNA donors, demonstrating the importance of validating touch DNA recovery techniques with a large pool of donors.touch DNA | direct amplification | forensic DNA analysis | trace evidence
The sampling of touch DNA from paper documents is often achieved by simply excising pieces of the document. This generates high-quality DNA profiles but also damages evidence; thus, we investigated non-destructive sampling of paper documents for touch DNA. Exploratory and confirmatory studies were performed to identify a non-destructive technique that generated excision-comparable STR profiles. Sampling with adhesive portions of sticky notes performed well in the initial exploratory study: in the confirmatory study this adhesive-based technique generated profiles of comparable completeness to conventional excision, with no significant difference in profile completeness found between the two. The sticky-note technique performs comparably to excision in generating STR profiles from paper, whilst preserving exhibit integrity.
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