Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part I: Instrumentation

Abstract

Building on the successful application in the laboratory of PLOT-cryoadsorption as a means of collecting vapor (or headspace) samples for chromatographic analysis, in this paper a field portable apparatus is introduced. This device fits inside of a briefcase (aluminum tool carrier), and can be easily transported by vehicle or by air. The portable apparatus functions entirely on compressed air, making it suitable for use in locations lacking electrical power, and for use in flammable and explosive environments. The apparatus consists of four aspects: a field capable PLOT-capillary platform, the supporting equipment platform, the service interface between the PLOT-capillary and the supporting equipment, and the necessary peripherals. Vapor sampling can be done with either a hand piece (containing the PLOT capillary) or with a custom fabricated standoff module. Both the hand piece and the standoff module can be heated and cooled to facilitate vapor collection and subsequent vapor sample removal. The service interface between the support platform and the sampling units makes use of a unique counter current approach that minimizes loss of cooling and heating due to heat transfer with the surroundings (recuperative thermostatting). Several types of PLOT-capillary elements and sampling probes are described in this report. Applications to a variety of samples relevant to forensic and environmental analysis are discussed in a companion paper.

Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part II: Applications

“…Subsequent to deposition, the solvent was slowly evaporated in a vacuum desiccator. The vapor collection from the vials of these compounds was done with the field portable PLOT-cryo apparatus described fully in Part I [1]. Multiple experiments were conducted to demonstrate both the hand piece and the standoff module and probe, in combination with both the single and multiple capillary wafers.…”

“…Part I describes the apparatus and sampling method [1]. We anticipate the utility of the field portable approach in a multitude of applications, for example, environmental and criminalistic sampling situations.…”

“…These samples are four of the benchmark analytes used in previous work to evaluate the performance of PLOT-cryo [1] and [6]. Use of these compounds and mixtures, the behavior of which in the vapor phase is well understood, enabled us to test the portable apparatus with a variety of test beds and matrices and to compare the results to those previously obtained with the laboratory-based PLOT-cryo approach.…”

Determination of cannabinoid vapor pressures to aid in vapor phase detection of intoxication

“…This modified approach provided us with the first generation of an in-the-field trace vapor collection device. Since the gravesoil work, a much more capable in-the-field trace vapor collection device has been built, which utilizes the air compressor from a typical fire truck to provide the suction and temperature control [29, 30]. No other energy inputs are necessary.…”

Composition of the C6+ Fraction of Natural Gas by Multiple Porous Layer Open Tubular Capillaries Maintained at Low Temperatures

“…This method has been described in detail previously. 59 The wafer itself was directly connected to the natural gas sample flow. This multi PLOT-cryo technique allows for the rapid trapping of relatively large quantities of a light and medium volatile analyte.…”