Comparison of the effects of sterilisation techniques on subsequent DNA profiling
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It is important that contamination from extraneous DNA should be minimised on items used at crime scenes and when dealing with exhibits within the laboratory. Four sterilisation techniques (UV, gamma and beta radiation and ethylene oxide treatment) were examined for their potential to degrade contaminating DNA to such an extent that subsequent DNA profiling was impossible. This work indicated that the most successful technique to reduce DNA contamination was ethylene oxide treatment. Of the radiation techniques tested in this study, gamma was the most successful at eradicating DNA and UV radiation was the least. None of the contaminated samples treated with ethylene oxide and subsequently subjected to DNA analysis met the DNA profile criteria necessary for acceptance on the UK National DNA Database. Contaminated cotton swabs and micro-centrifuge tubes treated with ethylene oxide showed a marked decrease in amplifiable DNA post-treatment. Ethylene oxide treatment to sterile swabs and tubes did not significantly affect subsequent DNA analysis.
KeywordsSterilisation DNA contamination Ethylene oxide Forensic science
The authors would like to thank the volunteers that donated samples for this work. The authors acknowledge the work and advice from Michael Turner and Tim Lester from Isotron, UK. Some of this work was conducted by KS and NB as part of their MSc Forensic Science, King’s College, London project conducted with the Metropolitan Police Service. The authors thank the staff at LGC Forensics, Teddington, UK for their invaluable help. The authors acknowledge the expertise and use of equipment provided by Dr. Matthew Arno, Genome Centre, King’s College, London.
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