Karl A. Reich

The ability to detect the presence of body fluids is a crucial first step in documenting and processing forensic evidence. The Rapid Stain IDentification (RSID™) tests for blood, saliva, semen and urine are lateral flow immunochromatographic strip tests specifically designed for forensic use. Like most lateral flow strips, the membrane components of the test are enclosed in a molded plastic cassette with a sample well and an observation window. No specialized equipment is required to use these tests or to score the results seen in the observation window; however, the utility of these tests can be enhanced if an electronic record of the test results can be obtained, preferably by a small hand-held device that could be used in the field under low light conditions. Such a device should also be able to “read” the lateral flow strips and accurately record the results of the test as either positive, i.e., the body fluid was detected, or negative, i.e., the body fluid was not detected. Here we describe the RSID™ Reader System—a ruggedized strip test reader unit that allows analysis and documentation of RSID™ lateral flow strip tests using pre-configured settings, and show that the RSID™ Reader can accurately and reproducibly report and record correct results from RSID™ blood, saliva, semen, and urine tests.

Abstract:  Current methods for forensic identification of saliva generally assay for the enzymatic activity of α‐amylase, an enzyme long associated with human saliva. Here, we describe the Rapid Stain IDentification (RSID™‐Saliva), a lateral flow immunochromatographic strip test that uses two antisalivary amylase monoclonal antibodies to detect the presence of salivary amylase, rather than the activity of the enzyme. We demonstrate that RSID™‐Saliva is accurate, reproducible, and highly sensitive for human saliva; RSID™‐Saliva detects less than 1 μL of saliva. The sensitivity of RSID^TM‐Saliva allows investigators to sample a fraction of a questioned stain while retaining the majority for DNA‐STR analysis. We demonstrate that RSID™‐Saliva identifies saliva from a variety of materials (e.g., cans, bottles, envelopes, and cigarette‐butts) and it does not cross‐react with blood, semen, urine, or vaginal fluid. RSID™‐Saliva is a useful forensic test for determining which evidentiary items contain saliva and thus may yield a DNA profile.