False positives caused by kitchen detergents in saliva testing with the blue starch agarose plate method

Abstract

False positivity is one of the major problems in interpreting assessment results. This study aimed to confirm the association of enzyme-contained kitchen detergents with false positives in saliva presumptive tests with the blue starch agarose plate method. Ten commercially available kitchen detergents were utilized as stain samples in the test. Six detergents (i.e., CHARMY Magica Enzyme Plus Orange Fragrances, CHARMY Magica Enzyme Plus Fresh Peach Fragrances, CHARMY Crysta Clear Gel, Cucute Lakumist, former products of CHARMY Magica Enzyme Plus Orange and Grapefruit Fragrances) generated false-positive reactions in the concentration ranging from undiluted to 64-fold diluted samples. Our results reveal that forensic experts should carefully interpret positive results of the blue starch agarose plate method from potentially detergent-mixed samples (e.g., glasses and chopsticks).