Abstract:
Skin is the largest organ of the human body and its importance in health has only just begun to be investigated. Compounds from skin have the potential to answer many questions. They can be used for diagnosis, monitoring pollutant exposure, and for understanding the skin microbiome. The ease with which skin can be sampled makes it an attractive choice for medical researchers. However, a major drawback of skin sampling is sample stability. Volatile samples quickly evaporate if left at room temperature, or are stored in inappropriate containers. To assess the feasibility of long term storage of skin samples, a pilot study using ‘Twister’ (Gerstel) stir bars was carried out. Skin surface samples were collected by rolling the stir bars on skin. Half of the bars were analysed immediately using thermal desorption GC-MS. The other half were stored at -80°C in glass 2 mL vials with inserts for four weeks, then were analysed in the same manner. After correction for compounds from field blanks, 330 compounds remained. These included fatty acids, alkanes, alkenes, azoles, amines, sulfides, aldehydes, acetates, ketones, terpenes, phthalates, and silicones. The majority (86%) remained stable over four weeks. Furthermore, the difference between stored and non-stored samples was smaller than differences between skin sample locations, which means the integrity of the metabolic profile was not compromised. Whilst this study was limited in size and requires large scale validation, storage of skin samples for long periods appears to be feasible, provided they remained unopened and are stored under cold conditions in suitable containers.
