Verification of a reduced sample extraction time for the RSID™-Saliva test

Screening for saliva forms an integral part of the workflow in any operational forensic laboratory and can assist in establishing physical contact between people, or people and objects, in an investigation. The RSID-Saliva test relies on the immunological interaction between antibodies specific for human α-amylase in the test strip, and the α-amylase antigen that is present in saliva. Since its implementation into the workflow at Forensic Science SA, a one hour sample extraction time was used prior to application to the RSID-Saliva test cassette. In this study, a shorter extraction time of one minute was investigated across a range of substrate types and saliva dilutions to assess its suitability for implementation. We found no significant difference between the one hour and one minute sample extraction on the time taken to obtain a positive RSID-Saliva result, indicating no loss of sensitivity when using the shorter extraction time. The time taken to obtain a positive RSID-Saliva test result was impacted by substrate type and saliva dilution. The one minute sample extraction time has thus been implemented in our laboratory to reduce turnaround times for saliva screening.