The trapped human experiment.

This experiment observed the evolution of metabolite plumes from a human trapped in a simulation of a collapsed building. Ten participants took it in turns over five days to lie in a simulation of a collapsed building and eight of them completed the 6 h protocol while their breath, sweat and skin metabolites were passed through a simulation of a collapsed glass-clad reinforced-concrete building. Safety, welfare and environmental parameters were monitored continuously, and active adsorbent sampling for thermal desorption GC-MS, on-line and embedded CO, CO(2) and O(2) monitoring, aspirating ion mobility spectrometry with integrated semiconductor gas sensors, direct injection GC-ion mobility spectrometry, active sampling thermal desorption GC-differential mobility spectrometry and a prototype remote early detection system for survivor location were used to monitor the evolution of the metabolite plumes that were generated. Oxygen levels within the void simulator were allowed to fall no lower than 19.1% (v). Concurrent levels of carbon dioxide built up to an average level of 1.6% (v) in the breathing zone of the participants. Temperature, humidity, carbon dioxide levels and the physiological measurements were consistent with a reproducible methodology that enabled the metabolite plumes to be sampled and characterized from the different parts of the experiment. Welfare and safety data were satisfactory with pulse rates, blood pressures and oxygenation, all within levels consistent with healthy adults. Up to 12 in-test welfare assessments per participant and a six-week follow-up Stanford Acute Stress Response Questionnaire indicated that the researchers and participants did not experience any adverse effects from their involvement in the study. Preliminary observations confirmed that CO(2), NH(3) and acetone were effective markers for trapped humans, although interactions with water absorbed in building debris needed further study. An unexpected observation from the NH(3) channel was the suppression of NH(3) during those periods when the participants slept, and this will be the subject of further study, as will be the detailed analysis of the casualty detection data obtained from the seven instruments used.

Evaluation of a new miniaturized ion mobility spectrometer and its coupling to fast gas chromatography multicapillary columns.

A new miniaturized ion mobility spectrometer (microIMS) has been constructed and evaluated. The results obtained for a selected group of volatile organic compounds have been compared with those provided by an IMS of bigger dimensions with satisfactory conclusions. Moreover, its performance in terms of analytes resolution is better than those values given for other miniaturized instruments described in the literature. The possibility of an adjustable shutter opening time and the low intensity of the radiation source are also remarkable characteristics of the miniaturized detector. The small size of the microIMS enables its portability and its wide-range of applications as a sensor device. Six different substances supposed as respiratory markers of different diseases have been selected to prove the feasibility of the spectrometer constructed.

Detection of sulfur-free odorants in natural gas using ion mobility spectrometry.

Beside the primary motivation of the public gas suppliers for odorizing natural gas with a sulfur-free odorant, which relates to the image of the environment-friendly fuel, natural gas, competing with low-sulfur heating fuel and diesel, a question of crucial importance of how to detect such sulfur-free odorants comes up. Concerning the replacement of sulfur-containing by sulfur-free odorization, the availability of a fast and sensitive detection method that can, further, be used on-site plays a key role. The minimum concentration of the new sulfur-free odorant Gasodor S-Free (S-Free) in natural gas should be added at a level of at least 8.8 mg m(-3) to assure a significant warning smell. Therefore, a dynamic range between 0 and approx. 25 mg m(-3) must be realised in the rather complex matrix of natural gas. By means of a handheld ion mobility spectrometer, the odorant content in natural gas is determined within less than 80 s total analysis time directly at the gas pipe. The concentration of S-Free is monitored between 4 and 23 mg m(-3) respecting the quality of the natural gas (high- and low-caloric gas). Results of the validation using a gas chromatograph as a reference standard will be discussed in detail.

Determination of acetone, 2-butanone, diethyl ketone and BTX using HSCC-UV-IMS.

A combination of a custom-designed ion mobility spectrometer (IMS) with a UV ionization source and a high speed capillary column (HSCC) has been developed as an analytical device for the sensitive detection of volatile organic compounds (VOCs), e.g. 2-propanone (acetone), 2-butanone and 3-pentanone (diethyl ketone) in the gas phase. A fast separation of the three selected substances and benzene, toluene and m-xylene (BTX) - all of which occur in human breath - has been achieved within less than four minutes at a carrier gas flow rate of 4.5 mL x min(-1). Multi-dimensional correlations presented support the interpretation of the acquired spectra of mixtures. Method detection limits were 2.7 microg x L(-1) for acetone and 2-butanone and 3.0 microg x L(-1) for diethyl ketone in nitrogen, respectively. The assay linear dynamic range is 4-320 microg x L(-1).

[Ion mobility spectrometer (IMS): a novel online monitor of trace volatile organic compounds].

The principle, character and developments of the instrument of ion mobility spectrometry are introduced, the applications of IMS to chemical warfare agents, explosives, drugs, environments monitoring and on-site industrial sensing are discussed, and some work on IMS in ISAS is represented.

A study of the spatial organisation of microbial cells in a gel matrix subjected to treatment with ultrasound standing waves.

Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been reported as a novel cell immobilisation technique. The spatial ordering of yeast cells, within suspensions subjected to an ultrasonic standing wave field, was analysed for the first time. A technique, based on 'freezing' the spatial arrangement using polymer gelation was developed. The resultant gel was then sectioned and examined using microscopic techniques. Light Microscopy confirmed the presence of specific regions in the ultrasonic field, where the cells are organised into bands corresponding to the standing waves' pressure nodal planes. Computer Image Analysis measurement of several physical parameters associated with this cell distribution matched the values derived from the theoretical model. The spatial cell-cell re-arrangement within each band and uneven distribution along the nodal planes have been analysed by Scanning Electron Microscopy. These results complement the ongoing study of the process of immobilisation of microbial cells by ultrasound standing waves.