The development of a rapid and reliable method (SAPSWash): for the extraction and recovery of spermatozoa from superabsorbent polymer containing products

This work presents a rapid and reliable method to recover spermatozoa from Super Absorbent Polymers (SAPs) commonly found in sanitary protection products such as nappies and sanitary towels. The use of salt solutions was investigated and a protocol was developed using a calcium chloride (CaCl2) solution to release semen deposited onto a selected SAP containing product. The method was tested on ultra-sanitary towel samples treated with a known amount of semen. A range of treatments were examined; some samples were prepared and immediately frozen for storage and others were allowed to air dry overnight to replicate the condition of similar items recovered for examination in sexual offence cases. The method allowed the collection of low yields of spermatozoa, but these were still sufficient for microscopic identification of intact heads and to obtain ESI17 DNA profiles from all the samples. This report presents the method, the results obtained and discusses prospective adaptations to the method for validation to implement the method into forensic casework.