Swab

Author : Tak Hou Fong
Publisher :
ISBN 13 : 9781321362480
Total Pages : pages
Book Rating : 4.3/5 (624 download)

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Download or read book Optimization of Drying Conditions of Sexual Assault Swabs written by Tak Hou Fong and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The California standard for preserving swabs collected during a sexual assault examination is to dry them for 60 minutes in a "swab dryer" (room temperature in an enclosed box with a fan). The swabs are then packaged in paper or cardboard for transport to a crime lab for serological testing, DNA testing, or both. Drying swabs in a swab dryer is time-consuming because forensic examiners must remain in the room to maintain chain of custody. Yet there is no published research demonstrating that drying sexual assault swabs in a swab dryer is necessary or that the current drying conditions (time and temperature) are optimal for preserving evidence. This study compared the quantity and quality of human DNA generated from mock sexual assault swabs saturated with either saliva or semen that were air dried overnight (no swab dryer) to the quantity and quality of human DNA generated from similar swabs that were dried in a swab dryer. Three different drying times (15, 30, and 60 minutes) and three different temperatures (ambient at 24°C; 37°C; and 56°C) were used with the swab dryer. The study further examined how different drying conditions affect swab dehydration as measured by the percent of weight lost during the drying process. My results indicate that although semen swabs were maximally dried under standard conditions (60 minutes at room temperature in a swab dryer), saliva swabs dried under standard conditions retained a mean of 30% of their wet weight and were not maximally dried until after they were packaged and allowed to air dry for several hours. By contrast, both saliva and semen swabs examined at higher temperatures (37°C and 56°C) dried in less than 60 minutes. In addition, both saliva and semen swabs that were air dried only (no swab dryer) yielded the same amount of DNA as swabs that were dried in a swab dryer (at all three different temperatures and different times) and then allowed to air dry. DNA quality likewise remained unaffected by drying method under the tested conditions; all samples yielded full STR profiles with no sign of degradation. Because the swabs were thoroughly saturated with semen or saliva before drying, my study mimicked the wettest swabs likely to be gathered from sexual assault victims. Therefore, my results suggest that drying swabs in a swab dryer may not be necessary under most casework conditions.