'We don't need your blood': revealing the opportunities in the complex and surprisingly individualised volatile organic compound profiles of human skin and saliva

Non-invasive techniques for in-vivo sampling of volatile organic compounds (VOCs) from human skin and saliva have been developed and characterised using polydimethyl siloxane (PDMS) as a sorptive material. These samplers have been analysed by thermal desorption (TD) in combination with gas chromatography – mass spectrometry (GC-MS) and applied to global, untargeted metabolic profiling studies of skin and saliva. The utility of an existing PDMS ‘Skin Patch’ for untargeted metabolic profiling studies has been evaluated and background artefact levels and sample storage stability shown to be key considerations. Successful storage of skin samples for up to 21 days at -80 ºC has been demonstrated. Evaluation of published methods reveals that existing methods for saliva sampling do not address the physical–chemical attributes of VOCs and evidence is presented for adopting in situ sampling of salivary VOCs directly from the oral cavity. [Continues.]