Cryofocused Sampling of Volatiles From Air Using Peltier-Assisted Capillary Microextraction – IP 1627

The analysis of VOCs in ambientair is currently performed with sorbent tubes following the guidelines from theEPA method TO-17. Some of the limitations observed for the analysis of VOCswith sorbent tubes include: long headspace extraction times (about an hour)with low flow rates and the use of expensive thermal desorption units coupledto gas chromatography-mass spectrometry (GC-MS) through the use of transferlines that can result in poor recoveries. FIU inventors have developed aCMV sampling device, which includes a thermoelectric cooler, a vacuum pump, atleast one holder for a capillary microextractor of volatiles (CMV) tube, and atleast one CMV tube. The thermoelectric cooler thermally contacts the holder andthe CMV tube, and the vacuum pump is fluidly connected to the CMV tube. The CMVtube can have a polydimethylsiloxane (PDMS) gel on glass fibers within a glasstube. The thermoelectric cooler can be a single-stage, dual-stage, ormulti-stage Peltier cooler. The CMV tube is cooled with an air stream beingdrawn through the CMV tube for a prescribed period of time. Air flow andcooling can be maintained for a period of 1 to 10 minutes at a temperature of-15 to 5°C. After sampling, the CMV with the absorbed diagnostic volatiles canbe placed in an ionized gas beam and introduced into a mass spectrometer orplaced in a thermal desorption unit (TDU), where, upon heating, the diagnosticvolatiles are released to an inlet port of an analytical instrument. Analyticalinstruments that can be used include gas chromatographs and ion mobilityspectrometers for separation and mass spectrometers for unambiguousidentification of the diagnostic volatiles. This CMV sampling device andmethods permit rapid extraction of VOCs in ambient air and have superiorperformance relative to the performance according to the reported guidelines ofthe EPA method TO-17. The sampling of volatilecompounds from air using the previously described CMV is enhanced by as much asby a factor of 4 times by cryofocusing the volatiles directly onto the CMV at-10 C. This device allows sampling of the headspace of indoor air, with manypotential applications including forensic chemical analysis. Anne Laure Schmitt Olivier aschmitt@fiu.edu 305-348-5948