Comparison of modern techniques for saliva screening

Area of Science:

• Forensic Science
• Biochemistry
• Analytical Chemistry

Background:

• Saliva stains are crucial in forensic investigations for corroborating DNA evidence.
• Presumptive saliva testing traditionally relies on amylase detection.
• Balancing presumptive testing with DNA analysis is critical due to sample consumption.

Purpose of the Study:

• To identify a specific and sensitive presumptive saliva screening test for forensic applications.
• To compare the sensitivity, specificity, and sample consumption of three modern saliva screening techniques.
• To evaluate test performance on mixtures and simulated casework samples.

Main Methods:

• Comparison of three saliva screening methods: SALIgAE, Phadebas, and starch-iodine mini-centrifuge test.
• Assessment of sensitivity, specificity, performance on mixtures, and simulated casework.
• Evaluation of sample volume consumed by each screening method.

Main Results:

• Phadebas demonstrated superior sensitivity, detecting neat saliva dilutions down to 1:200.
• SALIgAE and starch-iodine tests yielded considerably less sensitive results.
• Phadebas method minimizes sample consumption, maximizing DNA analysis potential.

Conclusions:

• The Phadebas method is a highly sensitive and specific presumptive saliva test suitable for forensic casework.
• Sensitive screening tests like Phadebas allow for comprehensive body fluid identification and DNA profiling.
• Optimizing presumptive testing balances probative value with the preservation of DNA for identification.