Real-time trace gas sensing of ethylene, propanal and acetaldehyde from human skin in vivo.

Trace gases emitted by human skin in vivo are monitored non-invasively and in real time using laser-based photoacoustic detection and proton-transfer reaction mass spectrometry. A small quartz cuvette is placed on the skin to create a headspace from which a carrier gas transports the skin emissions to the detection systems. The transparency of quartz to ultraviolet radiation (UVR) allows investigation of UVR-related trace gas emissions. As a demonstration of this measurement system, the effect of supplemental intake of systemic antioxidants on UVR-induced lipid peroxidation is investigated. The production by the skin of three biomarkers of UVR-induced lipid peroxidation (ethylene, acetaldehyde and propanal) is monitored. Although no significant effect of antioxidant intake was observed, the method presented here is a novel and promising technique for investigation of human skin in vivo.