Human skin volatiles: Passive sampling and GC × GC-ToFMS analysis as a tool to investigate the skin microbiome and interactions with anthropophilic mosquito disease vectors

Abstract

Volatile organic compounds (VOCs) emanating from the surfaces of human skin are of great interest to researchers in medical and forensic fields, as well as to biologists studying the ecology of blood-feeding insect vectors of human disease. Research involving the comparison of relative abundances of VOCs emanating from human skin is currently limited by the methodology used for sample collection and pre-concentration. The use of in-house developed silicone rubber (polydimethylsiloxane (PDMS)) passive sampling devices constructed in the form of bracelets and anklets was explored to address this need. The easy-to-use samplers were employed as non-invasive passive sampling devices for the non-targeted collection and concentration of volatile human skin emissions prior to thermal desorption thereof coupled with comprehensive gas chromatographic time-of-flight mass spectrometric (GC × GC-TOFMS) analysis. Compounds collected were from a wide range of compound classes. Several compounds, notably cyclic ketones, identified have not been previously reported in skin volatile literature. Comparison of normalized unique mass peak area signals has revealed relative quantitative differences and similarities between the samples collected from two individuals' wrists and as well as between an individual's wrist and ankle. The sampling method was evaluated based on its ability to provide many candidate compounds for potential biomarker discovery. The results show the ability of the new sampling method for augmenting the current knowledge on human skin volatile emissions. The samplers are both easy to use and economical. Applications explored include the study of the complex relationships between the human skin microbiome and the attractiveness of individuals to anthropophilic blood host seeking mosquitoes.

Analysis of brominated and chlorinated flame retardants, organophosphate esters, and polycyclic aromatic hydrocarbons in silicone wristbands used as personal passive samplers

“…The BFR-PAR (Brominated Flame Retardant -native compounds stock solution) mixture [including 10,15,17,28,30,47,49,66,71,77,85,99,100,119,126,[138][139][140]153,154,156,169,180,183,184,191,196,197,201,[203][204][205][206][207][208][209], pentabromoethyl benzene (PBEB), hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophenoxy)ethane (TBE), and decabromodiphenyl ethane (DBDPE)], BDE-MXE (Brominated Diphenyl Ether -native solution mixture) solution mixture 15,17,28,49,47,66,71,85,99,100,119,126,138,153,154,156,169,184,183,191,196,197,206,207,…”

“…As passive samplers, silicone wristbands work by chemical diffusion (absorption) of an environmental contaminant into the polymer of the silicone over time [4]. They were first introduced by O'Connell et al [5] in 2014 to assess exposure in an occupational setting, but have since been used in several studies, ranging from assessment of pesticide exposure among farmers in West Africa [6] and Peru [7] and flame retardant exposure among preschool children in the United States [4,8,9], to assessment of volatile organic chemicals emanating from the surface of human skin [10]. These studies have demonstrated that a commercial silicone wristband, worn by study participants, offers a non-invasive and simple way to quantify personal exposure to multiple chemicals from multiple microenvironments and within a multiday time period.…”

Endogenous and microbial volatile organic compounds in cutaneous health and disease

“…glass beads, cotton gauze, polydimethylsiloxane membranes) [12], [36], [37]. More recently, polydimethylsiloxane tubing has been employed as a wearable passive sampler looped around the wrist or ankle [38]. Volatiles can be recovered from these phases for subsequent analysis via thermal desorption, solvent extraction, or collection onto an adsorbent trap (e.g.…”

Advancements in Non-Invasive Biological Surface Sampling and Emerging Applications

“…Unconventional headspace extractive samplers including PDMS tubing sampling loops and silicone wristbands have been suggested in several studies for qualitative monitoring purposes. For instance, Roodt et al used PDMS tubing in a study investigating the relationship between skin microbiome and anthropophilic mosquito disease vectors [77]. PDMS tubing was cut (180 and 240 mm tubing length, 0.25 mm inner diameter) to manufacture sampler loops (Figure 5b).…”

“…(b) Wrist (left) and ankle (right) sampling using a PDMS loop passive sampling device. (c) c.1-2 bags used for transport that were attached to track participant ID and exposure time in the occupational deployments; c.3 single wristband deployment.Reproduced from[75,77,78], with permission from Elsevier and ACS Publishing, 2019.…”