EMER DUFFY*¹, MATTHEW R. JACOBS², AOIFE MORRIN¹
*Corresponding author
1. Insight Centre for Data Analytics, National Centre for Sensor Research, Dublin City University, Ireland
2. DCU Water Institute, School of Chemical Sciences, Dublin City University, Ireland

Abstract

Local skin chemistry was investigated in human participants using non-invasive approaches to characterise volatile organic compounds, cutaneous pH and tissue dielectric constants (TDC).
A total of 26 volatile compounds were identified through headspace solid-phase microextraction sampling with gas chromatography-mass spectrometry analysis. Acids and aldehydes were the predominant volatile species, accompanied by a variety of alcohols, ketones, hydrocarbons and esters. Measured values for pH and TDC were within the normal range for healthy skin. Principle component analysis classified participants into sub-groups, wherein specific volatile markers and skin pH were found to be strongly predictive of participant gender.

INTRODUCTION

Human skin is a region of high metabolic activity where secretion of a rich variety of biomarkers occurs throughout the stratum corneum (SC). Skin-derived volatile organic compounds (VOCs) are attracting increasing scientific and clinical interest as a non-invasive route to probe the body’s biochemistry for diverse applications including medical diagnostics (1), forensics (2), security (3) and the design of perfumes and deodorants (4). Studying skin VOCs requires a high degree of analytical sensitivity. Solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) has emerged as the method of choice in this regard, owing to the sensitivity and identification capabilities of MS coupled with the ease of performing headspace sampling via SPME (5,6).

Our skin is a constant source of VOCs which contain the footprints of cellular activities. As a result, VOCs can also reveal important biochemical information about the skin itself, with emerging reports of characteristic volatile profiles for chronic wounds (7), skin barrier impairment (8), and melanoma (9).
Skin VOCs are derived from apocrine, eccrine and ...