An investigation into the concurrent collection of human scent and epithelial skin cells using a non-contact sampling device.
In criminal investigations, the collection of human scent often employs a non-contact, dynamic airflow device, known as the Scent Transfer Unit 100 (STU-100), to transfer volatile organic compounds (VOCs) from an object/person onto a collection material that is subsequently presented to human scent discriminating canines. Human scent is theorized to be linked to epithelial skin cells that are shed at a relatively constant rate allowing both scent and cellular material to be deposited into the environment and/or onto objects. Simultaneous collection of cellular material, with adequate levels of nuclear deoxyribonucleic acid (nDNA), and human scent using a non-invasive methodology would facilitate criminal investigations. This study evaluated the STU-100 for the concurrent collection of human scent and epithelial skin cells from a porous (paper) and non-porous (stainless steel bar) object that was held for a specified period of time in the dominant hand of twenty subjects (10 females and 10 males). Human scent analysis was performed using headspace static solid-phase microextraction with gas chromatography-mass spectrometry (HS-SPME/GC-MS). A polycarbonate filter was used to trap epithelial skin cells which, upon extraction, were subsequently analyzed, inter-laboratory, using the quantitative polymerase chain reaction (qPCR). The STU-100 proved to be inadequate for collecting the minimum number of epithelial skin cells required to obtain nuclear DNA concentrations above the limit of detection for the qPCR kit. With regard to its use for human scent collection, a reduction in the number and mass of compounds was observed when compared to samples that were directly collected. However, when the indirect collection of human scent from the two different objects was compared, a greater number and mass of compounds was observed from the non-porous object than from the porous object. This outcome suggests that the matrix composition of the scent source could affect the efficacy of the human scent collected when using a non-contact, dynamic airflow sampling device. The findings from this study are of importance because although the STU-100 proved to not be suitable for collecting epithelial skin cells for DNA analysis, its non-contact capability allows for the possibility of other potential forensic evidence, like that of human scent, to be obtained.
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States.
Norma Iris
NI
Caraballo
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Biological Sciences, Florida International University, Miami, FL, United States.
Julian
J
Mendel
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States.
Howard
H
Holness
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Biological Sciences, Florida International University, Miami, FL, United States.
Joel
J
La Salvia
Forensic and Investigative Science, West Virginia University, Morgantown, WV, United States.
Tina
T
Moroose
Counterterrorism and Forensic Science Research Unit, FBI Laboratory, Quantico, VA, United States.
Brian
B
Eckenrode
Evidence Response Team Unit, FBI Laboratory, Quantico, VA, United States.
Rex
R
Stockham
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Chemistry and Biochemistry, Florida International University, Miami, FL, United States.
Kenneth
K
Furton
International Forensic Research Institute, Florida International University, Miami, FL, United States; Department of Biological Sciences, Florida International University, Miami, FL, United States. Electronic address: millsd@fiu.edu.
DeEtta
D
Mills
D004847:Epithelial Cells / Q000166:cytology*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D009812:Odorants / Q000032:analysis*; D012867:Skin / Q000166:cytology; D052617:Solid Phase Microextraction; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000302:isolation & purification
D055549:Volatile Organic Compounds
DNA transfer; Epithelial cells; GC–MS; Human scent; SPME; Volatile organic compounds (VOCs)