Detection of saliva using Seratec Amylase Paper
OA Version
Citation
Abstract
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.