Permeation profiles of potential urine-borne biomarkers of human presence over brick and concrete

Abstract

Headspace solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS) analysis was performed over an in-house made filling chamber loaded with brick or concrete, mimicking a potential entrapment scene of building collapse following natural or man-made disasters. Permeation profiles of 22 volatile species, released by human urine samples, were quantitatively monitored over the selected debris materials for a time period of 24 hours (LODs ranged from 0.05–0.8 ppb, R² varied from 0.991–0.999 and RSDs 3–9%). Ketones were the most abundant constituents of urine vapor with eleven representatives followed by five aldehydes, two furans, two sulphur-containing compounds, one nitrile and one heterocyclic compound. The majority of the detected compounds were found below 10 ppb, with the exception of some ketones including acetone, 2-butanone and 2-pentanone. The influence of debris materials on the permeation profiles of analytes under study depended on their fundamental physicochemical properties. Less volatile and more soluble compounds in urine (ketones and aldehydes) were found to be present for longer time periods in the surroundings of the urine samples than the more volatile and poorly soluble ones (furans, sulphur-containing compounds). More specifically, ketones exhibited longer residence times in the filling chamber and strongly interacted with the debris materials as their molecular masses were increased; their profiles were found to be significantly modified in the presence of concrete. In general, concrete demonstrated a stronger interaction with urine species than brick, affecting the observed concentrations and residence times of released volatiles in the chamber.