An Optimized Centrifugal Method for Separation of Semen From Superabsorbent Polymers for Forensic Analysis

• NCJ Number: 251981
• Author(s): Lucy R. Camarena, Bailey K. Glasscock, Demi Daniels, Nicolle Ackley, Marybeth Sciarretta, Sarah J. Seashols-Williams
• Date Published: March 2017
• Length: 6 pages
• Agencies: NIJ-Sponsored
• Award: NIJ/FSF Forensic Science Student Research Program

Annotation

This study evaluated the impact of super absorbent polymers (SAPs) on the current forensic DNA workflow, developing an efficient centrifugal protocol for separating spermatozoa from material that contains SAPs.

Abstract

Connection of a perpetrator to a sexual assault is best performed through the confirmed presence of semen, thereby proving sexual contact. Evidentiary items can include sanitary napkins or diapers containing SAPs, complicating spermatozoa visualization and DNA analysis. The optimized filtration method was compared to common practices of excising the top layer only, resulting in significantly higher sperm yields when a core sample of the substrate was taken. Direct isolation of the SAP-containing materials without filtering resulted in 20 percent sample failure; additionally, SAP material was observed in the final eluted DNA samples, causing physical interference. Thus, use of the described centrifugal-filtering method is a simple preliminary step that improves spermatozoa visualization and enables more consistent DNA yields, while also avoiding SAP interference. (Publisher abstract modified)