Monitoring of Selected Skin-Borne Volatile Markers of Entrapped Humans by Selective Reagent Ionization Time of Flight Mass Spectrometry in NO+ Mode

ABSTRACT: Selective reagent ionization time-of-flight mass spectrometry with NO+ as the reagent ion (SRI-TOF-MS (NO+)) was applied for near real-time monitoring of selected skin-borne constituents which are potential markers of human presence. The experimental protocol involved a group of 10 healthy volunteers enclosed in a body plethysmography chamber mimicking the entrapment environment. A total of 12 preselected omnipresent in human scent volatiles were quantitatively monitored. Among them there were six aldehydes (n-propanal, n-hexanal, n-heptanal, n-octanal, n-nonanal, and 2 methyl 2-propenal), four ketones (acetone, 2-butanone, 3-buten-2-one, and 6-methyl-5-hepten-2-one), one hydrocarbon (2-methyl 2-pentene), and one terpene (DL-limonene). The observed median emission rates ranged from 0.28 to 44.8 nmol × person−1 × min−1 (16−1530 fmol × cm−2 × min−1). Within the compounds under study, ketones in general and acetone in particular exhibited the highest abundances. Th