# Chemical Characterization of Human Body Odor Headspace Components
## 3 Results
### Comparison of Whole-Body Chamber Samples and Individual Biospecimens  
The objective of phase 2 was to evaluate the chemical odor profile of hand, breath, and axillary odor samples collected directly from their respective areas. The aim was to analytically evaluate the volatile organic compounds (VOCs) from each body location and evaluate individual specimen VOCs as well as observe inter-specimen variations across the population sampled. Across whole-body sampling and individual biospecimens, there were a total of 183 different compounds. From whole-body sampling, 105 compounds were detected. Among hand samples, 76 compounds were detected; 73 were detected from the axillary samples, and 10 were detected from the breath samples. The low number of compounds detected from the breath samples could be a result of the collection method. Unlike the hand and axillary collection methods, which involved direct contact with the collection substrate, the procedure to collect breath was somewhat indirect, as it involved the participants blowing into a vial via a mouthpiece. The ten compounds identified from the breath samples of the ten subject participants included.alpha.-Pinene; 1,2,4-Methenoaxulene, decahydro-1,5,5,8a-tetramethyl-, [1S-(1.alpha.2.alpha.3a.beta.4.alpha.8a.beta.9R*)]; decanal; dodecane; ethanol, 2-(2-ethoxyoxythoxy)-; ethanone, 1-(1-cyclohex-1-yl)-; longifolene; nonanal; octanal; and undecane. While other studies have reported about 200 different VOCs detected from breath, the compounds identified within the present study corroborate these frequently occurring compounds in breath [29; 40]. Among the hand samples, compounds with a frequency of 70% or more (detected in \(\geq\)7 subject participants) included: 1-Hexanol, 2-ethyl-; 2-Furamethanol; 4-Cyanocyclohexene; 5-Hepten-2-one, 6-methyl-; benzyl alcohol; decanal; decanoic acid, methyl ester; ethanol, 2-(2-ethoxyoxythoxy)-; heptanal; hexadecane; exanal; nonanal; octanoic acid, methyl ester; tetradecane; and undecane. Previous studies focusing on hand odor have also identified these compounds [2; 5; 40; 25]. Additionally, in a recent review of previous studies of human scent VOCs, [PERSON] et al. [2] identified nonanal and decanal as being the two highest-frequency compounds from human hand odor, as they were present in the previous studies reviewed. This study corroborates this finding, as nonanal and decanal were also the two highest-frequency compounds identified among the hand samples. The axillary samples were composed of a wider range of compounds; however, they consisted of lower frequencies, with fecal and nonanal being the only ones with a frequency of 70% or higher. Octanal and undecane had a frequency of at least 50%. [PERSON] et al. studied the VOCs present within the headspace of axillary sweat samples of various individuals and also reported a majority of the compounds identified in the present study [21]. Figure 6 depicts a graph of the odor profiles retrieved from the different sample types (chamber, hand, axillary, breath) of Female 1 and Male 1. For the representative female individual, a total of 50 different primary odor compounds were detected across all sample types. Of these 50, there were 21 detected from the chamber, 36 detected from hand, 7 detected from axillary, and 5 detected from breath. While the hands emitted the highest number of compounds, the odor profile captured from the chamber displays compounds with greater abundances. The odor profiles of the axillary and breath samples consist of fewer compounds than the chamber and hand samples; however, the compounds that are present within these biospecimens have a higher ratio within their odor profile. Of the fifty different compounds that were detected among the different sample types, only two were present in all four: decanal and nonanal. Following with a frequency of 75% within this individual was the compound octanal. The remaining compounds depicted a frequency of 50% or lower, as these were only present in either two or one sample type.