Evaluation of a saliva presumptive test using the α-amylase assay kit

Abstract

 Saliva presumptive tests, which use the blue starch agarose plate method, are simple and sensitive tests; however, they are not suitable for crime scene investigations or urgent cases. The aim of this study was to evaluate the forensic application of a 2-chloro-4-nitrophenol (CNP)-based saliva presumptive test using the α-amylase assay kit which is a commercial brewing analysis kit. The sensitivity and specificity of the saliva presumptive test were validated using diluted saliva stains and various body fluid stains. The forensic applicability of the test was evaluated using mock forensic samples to compare results from the CNP-based method and blue starch agarose plate method. The α-amylase activity was qualitatively detected from diluted saliva stains (4 μL) and different donor-derived saliva stains (n=21) after reaction at room temperature for 10 min. All mock forensic samples produced concordant results from the two saliva presumptive tests. Our results indicate that the CNP-based saliva presumptive test combined with the α-amylase assay kit is rapid, simple, and useful for on-site examination.