Detection of saliva on combustible and electronic cigarettes using the SERATEC Amylase Test and subsequent DNA analysis
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Saliva can be detected on items including cigarette butts, glassware, clothing, human skin and condoms, and the identification of saliva on these types of evidence may be important to provide linkages or investigative leads in forensic cases. Sometimes when the presence of saliva is indicated, the item will be sent for deoxyribonucleic acid (DNA) analysis and may be used for identification of individuals involved in a crime. The detection of saliva mostly depends on the activity and the presence of amylase. The SERATEC® Amylase Test (SERATEC GmbH, Goettingen, Germany) is a lateral flow immunochromatographic test that targets the presence of human α-Amylase using two monoclonal anti-human-α-Amylase antibodies. This study investigates the effectiveness of using the SERATEC® Amylase Test to detect amylase on cigarette butts and vaping devices. In addition, the possible correlation between the SERATEC® Amylase Test result and the amount of DNA extracted from cigarette butt samples is evaluated. Results indicated that the cigarettes and vaping devices tested had no inhibitory effect on the SERATEC® Amylase Test. The SERATEC® Amylase test was able to detect amylase from various brands of cigarettes, marijuana cigarettes, JUULpods™ (JUUL Labs™ Inc., San Francisco, CA) and an additional vaping device. Negative amylase test results (22 of 114 samples) may be attributable to personal smoking habits and the texture of the cigarette butt wrap paper or vaping device. DNA quantification results indicated that the majority of cellular material was retained on the wrap paper even after submersion in the SERATEC® Amylase Test buffer. It is recommended that the wrap paper from the cigarette filter and the remaining extract from preliminary testing be combined prior to DNA extraction in order to maximize total DNA recovered from a cigarette sample. The correlation between the SERATEC® Amylase Test result and the quantity of DNA extracted from the same source was not linear. The presence of saliva and DNA concentration are controlled by different factors, thus using the detection of saliva to predict the recoverability of DNA on cigarettes may be valuable in some situations, but is not precise.