When searching scenes or collecting evidence, it is often helpful to perform a presumptive test for the presence of semen on those stains that fluoresce under UV light. The seminal fluid test is very easy to perform. Simply transfer part of the suspected stain to the provided transfer paper with sterile water contained in the first vial, then squeeze the second applicator to crush the glass ampule inside. Shake the applicator for a few seconds to ensure complete mixing of the components, remove the applicator cap, and gently squeeze the applicator to apply the reagents to the transferred stain. A positive result is indicated by a deep purple color.