Trace determination of airborne polyfluorinated iodine alkanes using multisorbent thermal desorption/gas chromatography/high resolution mass spectrometry.

A novel gas chromatography/high resolution mass spectrometry method coupled with multisorbent thermal desorption cartridges has been developed for the determination of volatile neutral polyfluorinated iodine alkanes (PFIs) in airborne samples. It allows, for the first time, simultaneous analysis of four mono-iodized perfluorinated alkanes, three diiodized perfluorinated alkanes and four mono-iodized polyfluorinated telomers in ambient air samples. 3.75 L air sample was passed through a sorbent tube packed with 150 mg of Tenax TA and 200mg of Carbograph 1 TD for analyte adsorption. Important factors during the analysis procedures, such as safe sampling volume, air sampling rate, analyte desorption and transfer strategies, were optimized and good thermal desorption efficiencies were obtained. The method detection limit (MDL) concentration ranged from 0.04 pg/L for 1H,1H,2H,2H-perfluorododecyl iodide to 1.2 pg/L for perfluorohexyl iodide, and instrument response of a seven-point calibration was linear in the range of 10-1000 pg. Travel spike recoveries ranged from 83% to 116%. Small variabilities of less than 36% were obtained near the MDLs and the differences between triplicates were even smaller (2.1-7.3%) at 200 pg spiked level. The method was successfully applied to analyze ambient air samples collected near a point source, and five PFIs were identified (10.8-85.0 pg/L), with none of the analytes detectable at the background site.