Ion mobility spectrometry for detection of skin volatiles

Abstract

Volatile organic compounds (VOCs) released by humans through their skin were investigated in near real time using ion mobility spectrometry after gas chromatographic separation with a short multi-capillary column. VOCs typically found in a small nitrogen flow covering the skin are 3-methyl-2-butenal, 6-methylhept-5-en-2-one, sec-butyl acetate, benzaldehyde, octanal, 2-ethylhexanol, nonanal and decanal at volume fractions in the low part per billion-(ppb) range. The technique presented here may contribute to elucidating some physiological processes occurring in the human skin.

Fig. 1

Set-up of GC–IMS. The stainless steel pan used for skin VOC sampling was tightly fixed to the navel/umbilicus of the volunteer using a bandage. The pan was rinsed with nitrogen flow (3 ml/min) and its outlet was directly connected to the sample loop integrated in the GC–IMS device.

Fig. 2

(a–h) Calibration curves of the selected compounds measured with GC–IMS.

Fig. 3

3D-visualization of IMS-chromatogram of emitted skin VOCs. Drift time and retention time are presented in X- and Y-axis, respectively, and peak height is displayed using colour-scale.

Fig. 4

(a and b) Concentration profile of octanal and nonanal detected in gas samples collected above skin.

Fig. 5

(a) Concentration profile of decanal detected in skin samples of seven volunteers; (b) increasing emitted concentration values for decanal during skin experiments.

Fig. 6

(a and b) Concentration profile of 3-methyl-2-butenal and benzaldehyde detected in skin gas samples.

Fig. 7

(a) Concentration profile of sec-butylacetate detected in gas samples collected above skin; (b) decrease of sec-butylacetate concentration during skin measurements.

Fig. 8

(a and b) Concentration profile of 2-ethyl-hexanol and 6-methylhept-5-en-2-one detected in skin samples.