Improvements in the vapor-time profile analysis of explosive odorants using solid-phase microextraction.

A modified approach for characterization of the vapor-time profile of the headspace odors of explosives was developed using solid-phase microextraction (SPME) incorporating introduction of an externally-sampled internal standard (ESIS) followed by gas chromatography/mass spectrometry (GC/MS) analysis. With this new method, reproducibility of the measurements of 2-ethyl-1-hexanol and cyclohexanone were improved compared to previous work (Hoffman et al., 2009; Arthur and Pawliszyn, 1990) through the use of stable-isotope-labeled internal standards. Exposing the SPME fiber to the ESIS after sampling the target analyte proved to be advantageous, while still correcting for fiber variability and detector drift. For the analysis of high volatility compounds, incorporation of the ESIS using the SPME fiber in the retracted position minimized the subsequent competitive loss of the target analyte, allowing for much longer sampling times.

Evaluating headspace component vapor-time profiles by solid-phase microextraction with external sampling of an internal standard.

The vapor-time profiles of explosive materials are of valuable interest to Homeland Security, providing critical information that can aid in the detection of explosive-containing devices. An approach is described that achieves reproducible characterization of volatile components as a function of time based on comparison of the sample response to an externally sampled internal standard (ESIS). Utilizing nonequilibrium solid-phase microextraction (SPME) measurements, this SPME-ESIS technique improves reproducibility (reported as percent relative standard deviation) of vapor-time profiles by approximately an order of magnitude and allows for an equitable comparison of the target compound between diverse materials. Two odorants associated with canine detection of explosives, 2-ethyl-1-hexanol and 2,4-dinitrotoluene, are used to optimize parameters for the SPME-ESIS technique.

Indoor air pollution by 2-ethyl-1-hexanol in non-domestic buildings in Nagoya, Japan.

2-Ethyl-1-hexanol is a possibly causative chemical in sick building symptoms, although 2-ethyl-1-hexanol has received little attention as a hazardous substance in studies on indoor air pollution. Airborne 2-ethyl-1-hexanol concentrations were measured from 2002 to 2004 in 99 rooms of 42 non-domestic buildings in Nagoya, Japan. The diffusive sampling method is effective for the measurement of a low level of 2-ethyl-1-hexanol in indoor air. The geometric mean (geometric standard deviation) of 2-ethyl-1-hexanol concentrations was 16.5 (5.4) microg m(-3) in indoor air and 1.9 (2.2) microg m(-3) in outdoor air. The maximum concentration of 2-ethyl-1-hexanol in indoor air and outdoor air was 2709 microg m(-3) and 12.4 microg m(-3), respectively. Fewer rooms in a small number of new buildings showed high concentrations of 2-ethyl-1-hexanol, while low concentrations were observed in many rooms of these buildings as well as the other new buildings. The room-to-room concentrations of 2-ethyl-1-hexanol in each building exhibited a wide variation. The geometric mean of the 2-ethyl-1-hexanol concentrations was significantly higher for indoor air than for outdoor air (p < 0.01). The correlation of the 2-ethyl-1-hexanol concentrations between indoor and outdoor air was not significant. Mechanical ventilation was effective in the temporary reduction of indoor 2-ethyl-1-hexanol level. These results suggest that the predominant source of 2-ethyl-1-hexanol was indoor areas.