Characteristic Human Scent Compounds Trapped on Natural and Synthetic Fabrics as analyzed by SPME-GC/MS

Abstract

The collection of human odor volatiles is of interest to forensic applications as a path to investigate canine scent discriminations in legal investigations. A study using a selected array of previously identified human odor compounds has been conducted to determine the retention and release capabilities of five (5) natural and synthetic fabric types, cotton (mercerized fabric and gauze matrix), polyester, rayon and wool. A direct spike approach as well the use of a dynamic airflow device were the two approaches used for the collection of the selected volatile organic mix. The direct spike experiment showed how natural, cellulosic fibers such as viscose rayon showed an enhanced ability to release a reproducible volatile odor profile. Rayon demonstrated to be the fabric type with the highest recovered scent mass amounts, followed by wool and polyester. As was expected cotton showed the lowest recovered amounts, possibly due to its complex fiber morphology which enhances the possibility of chemicals to be retained in higher rates within the structure of the cotton fiber. Samples collected on the same fabric substrate showed a reproducible odor profile as measured via hierarchical clustering which corroborates previous live human odor studies and which can be pivotal in forensic biometric measurements. The introduction of an airflow variable to volatile collection decreased the amounts recovered for all fiber types. The reproducibility for each fabric type between replicate sampling was also reduced and a statistical significant difference (P<0.001) was observed in the interaction between airflow speed and fabric type. The cotton fabric was the material which showed enhance collection at the low airflow speed as observed by the recovered mass amount. In conclusion, these findings do indicate that chemical retention is strongly affected by fiber type and outside environmental variables such as airflow, which can alter the odor profile of a collected scent sample.