Signal intensities of exemplary analytes that accumulate during hemodialysis.

<p>Signal intensities of analytes P9 and P11 in 28 healthy controls, 26 patients with chronic renal failure (CRF) stage 2–4 according to K/DOQI-criteria, 28 patients with end-stage renal disease (ESRD, CRF stage 5D) prior to and 22 after hemodialysis. Signal intensities were tested for statistical significance by two-tailed t-tests; *p<0.05, **p<0.01, ***p<0.001.</p

Experimental parameters of the multi-capillary column ion mobility spectrometer (MCC/IMS) as used in the present study.

*<p>Multichrom, Novosibirsk, Russia.</p

Receiver-operating-characteristic (ROC) curves to distinguish different stages of renal failure.

<p>ROC curves for the sum of the signal intensities of hydroxyacetone, hydroxy-2-butanone, ammonia, 0.5468–17.0, and 0.5985–55.6 in differentiating (A) healthy subjects and patients with chronic renal failure (CRF) corresponding to an eGFR of 10–59 ml/min per 1.73 m² (AUC 0.76), (B) healthy subjects and patients with endstage renal disease (ESRD, AUC 0.83), and (C) healthy subjects and all patients with impaired renal function (CRF and ESRD; AUC 0.80).</p

Signal intensities of exemplary analytes that accumulate with decreasing renal function and are eliminated by dialysis.

<p>Figures A–C present signal intensities of exemplary analytes P1–P3 and Figure D the sum of the signal intensities of the five analytes that accumulate with decreasing function and are eliminated by dialysis (P1–P5) in 28 healthy controls, 26 patients with chronic renal failure (CRF) stage 2–4 according to K/DOQI-criteria, 28 patients with end-stage renal disease (ESRD, CRF stage 5D) prior to and 22 after hemodialysis. Signal intensities were tested for statistical significance by two-tailed t-tests; *p<0.05, **p<0.01, ***p<0.001.</p

Representative multi-capillary column/ion mobility spectra (MCC/IMS) of breath samples.

<p>Breath sample of (A) a healthy adult, (B) an end-stage renal disease proband before and (C) after hemodialysis treatment. Areas of interest are marked and labeled by numbers. Substances corresponding to these numbers are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046258#pone-0046258-t002" target="_blank">Table 2</a>. Signal intensity is coded by colours (yellow: very high; red high, blue: moderate, white: no signal).</p

Scheme of an ion mobility spectrometer (MCC/IMS).

<p>The multi-capillary column (MCC) provides a preseparation of the molecules in the gas phase. In the ionization chamber proton transfer from the reactant ions to the analyte molecules takes place, thus forming protonated analyte ions. The drift time of the ions in the electric field depends on size and shape of the analytes. The retention time in the MCC and mobility in the IMS characterize the identity of the analyte. The intensity of the signal is a measure of the analyte's concentration.</p

Detection of metabolites of trapped humans using ion mobility spectrometry coupled with gas chromatography

For the first time, ion mobility spectrometry coupled with rapid gas chromatography, using multicapillary columns, was applied for the development of a pattern of signs of life for the localization of entrapped victims after disaster events (e.g., earthquake, terroristic attack). During a simulation experiment with entrapped volunteers, 12 human metabolites could be detected in the air of the void with sufficient sensitivity to enable a valid decision on the presence of a living person. Using a basic normalized summation of the measured concentrations, all volunteers involved in the particular experiments could be recognized only few minutes after they entered the simulation void and after less than 3 min of analysis time. An additional independent validation experiment enabled the recognition of a person in a room of ∼25 m3 after ∼30 min with sufficiently high sensitivity to detect even a person briefly leaving the room. Undoubtedly, additional work must be done on analysis time and weight of the equipment, as well as on validation during real disaster events. However, the enormous potential of the method as a significantly helpful tool for search-and-rescue operations, in addition to trained canines, could be demonstrated

Detection of Metabolites of Trapped Humans Using Ion Mobility Spectrometry Coupled with Gas Chromatography

For the first time, ion mobility spectrometry coupled with rapid gas chromatography, using multicapillary columns, was applied for the development of a pattern of signs of life for the localization of entrapped victims after disaster events (e.g., earthquake, terroristic attack). During a simulation experiment with entrapped volunteers, 12 human metabolites could be detected in the air of the void with sufficient sensitivity to enable a valid decision on the presence of a living person. Using a basic normalized summation of the measured concentrations, all volunteers involved in the particular experiments could be recognized only few minutes after they entered the simulation void and after less than 3 min of analysis time. An additional independent validation experiment enabled the recognition of a person in a room of ∼25 m³ after ∼30 min with sufficiently high sensitivity to detect even a person briefly leaving the room. Undoubtedly, additional work must be done on analysis time and weight of the equipment, as well as on validation during real disaster events. However, the enormous potential of the method as a significantly helpful tool for search-and-rescue operations, in addition to trained canines, could be demonstrated