DNA analysis of saliva traces on cigarette butts exposed to indoor and outdoor environmental conditions

Abstract

The examination of saliva traces left on cigarette butts as evidences are complicated due to the availability of biological material in trace amounts and its rapid degradation due to extreme effects of envi ronmental factors. This study is aimed to ass ess the DNA purity and quantify the amount of DNA preserved in saliva found on cigarette butts subjected to various tem peratures and humidity. Cigarette butt samples were smoked collected and were exposed to outdoors and indoors for 1 day, 3 days and 7 days , respectively . The samples were subjected to DNA extraction, quantification and DNA profiling. The DNA purity on ciga rette butts in indoor experiment was found to be higher (A 260/280 1.76 – 1.91) than the purities of outdoor experiment (A 260/280 1.26 – 1.65) . The concentration of DNA found on the saliva traces on cigarette butts can be very variable in outdoor experiment al set - up (377.99 – 585.83 ng/μL) compared to indoor (266.38 – 290.18 ng/μL); attributable to the differences in humidity as well as temperature. In conclusion, the purity obtained in this study ranged from low to high, and samples with intermediate to hig h purity was proven , allowing DNA profiling. Since the concentration of DNA reported in this study may constitute human as well as non -human DNA, the interpretation of the DNA purity is a better mean for elucidating its potential value in forensic aspect compared to DNA concentration.