Reproducible vapor-time profiles using solid-phase microextraction with an externally sampled internal standard.

Determination of the dynamic nature of vapor/odor release has application in a wide variety of systems. This study applies automated solid-phase microextraction (SPME) utilizing an externally sampled internal standard (ESIS) to determine the vapor-time profile of odor delivery devices for three classes of explosive compounds. The profiles of delivery systems for target odorants 2,4-dinitrotoluene (2,4-DNT), 2-ethyl-1-hexanol (2-EH), and triacetone triperoxide (TATP) as canine training aids were compared over a period of 70 h. Strategies for evaluating the vapor-time profile of components with widely differing volatility are considered. An approach to quantifying the vapor concentration is described. The differences in the vapor-time profiles are examined and suggestions for selecting the best representative odor delivery technique are outlined.