Biological fluids, like saliva, are commonly encountered in forensic casework. The ability to locate and identify the type of biological fluid on a piece of evidence can lead to further testing including DNA extraction and analysis. Saliva stains are often found on a variety of surfaces in the presence of additional bodily fluids. Many of these stains cannot be readily seen, which makes detection difficult. A study utilizing mapping with Seratec® Amylase Paper and the use of an alternative light source (ALS) for better visibility and detection was conducted to test the effectiveness of this medium. Five different types of stains were prepared, including saliva, saliva and blood, saliva and semen, saliva and urine, and saliva, blood, semen, and urine. The stains were deposited onto four different textile types, including cotton, denim, fleece, and spandex. The results indicated that the presence of other body fluids may adversely affect the detection of saliva using Seratec® Amylase Paper. In order to effectively test whether the Amylase Paper itself inhibited DNA extraction and quantification, only half of each saliva stain was mapped with the paper. This left half of the stain untouched, and available for a comparative DNA study. The same saliva donor, donor C, was used for the entirety of the DNA study, and stains were extracted from the cotton and fleece textiles. A Harris micro-punch was used to collect identical 3mm samples from the portion of the stain in contact with the Amylase Paper and the portion of the same stain not in contact with the Amylase Paper. In addition, samples of the Amylase Paper that had not been used for previous testing were tested to see if the internal positive control (IPC) was affected by the paper itself. The results of the DNA extraction and quantification showed no inhibition in the samples in contact with the Amylase Paper, the samples not in contact with the Amylase Paper, nor from the Amylase Paper itself. These results show that Seratec® Amylase Paper can identify saliva in most mixed samples including blood, semen, and urine. In addition, the application of the Amylase Paper does not inhibit or prevent the subsequent extraction or quantification of DNA, and allows for samples in contact with Amylase Paper to be used for DNA testing downstream. Seratec® Amylase Paper is an effective screening method in forensic casework when the presence of saliva is suspected and can be used even when DNA testing is anticipated in the future.

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.