Date of Award
Spring 5-2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department/Program
Forensic Science
Language
English
First Advisor or Mentor
Mechthild Prinz
Second Reader
Michelle Gordon O’Rourke
Third Advisor
Grace Axler-DiPerte
Abstract
As the significance of trace DNA has increased over time, it has become more important to optimize each process to avoid any loss of genetic material. Factors that could negatively affect the quality and quantity of DNA during transport or storage include environmental temperature, the DNA collection devices, the packaging, and possible contamination. This study compared the DNA stability of saliva stain swabs collected by moistening the swab with deionized water or Sample Keeper and stored at room temperature. Sample Keeper (Microread Genetics, Beijing) is a proprietary buffer marketed as a DNA stabilizing agent. We swabbed 110 saliva stains from five donors with deionized water and Sample Keeper and tested them at defined times from day 1 to 270. Swabs were extracted, quantified, and analyzed for STR genotypes. The DNA quality assessments performed included DNA concentration, degradation index (DI), ski slopes, heterozygous allele ratios, and paired t-tests between the Sample Keeper and deionized water with a 95% confidence level. The results indicate that Sample Keeper has similar swabbing efficiency to deionized water. Sample Keeper resulted in a slight decrease in degradation index and lessened ski-slope effects over 270 days. The STR profile quality was still perfect for all samples without drop-outs. Further experimentation is necessary to determine the effectiveness of the Sample Keeper, using longer collection periods or as a stability solution, trace DNA, and testing under various storage conditions, including exposure to humidity, light, and bacteria.
Recommended Citation
Lu, Kuanwei, "Stability of DNA in saliva evidence collected with two different swabbing solutions" (2024). CUNY Academic Works.
https://academicworks.cuny.edu/jj_etds/314