A new preconcentration technique utilizing “Active SPME” has eliminated the deficiencies found with the canister technique, allowing recovery of heavy molecular weight compounds through C24 while being more compatible with thermally labile compounds than thermal desorption tubes. The multi-trap preconcentrator utilizes a “flow through” SPME stage where sample is actively introduced across the SPME film, eliminating the matrix and temperature variations found in classical “diffusive” SPME. Compounds from C10 and heavier are retained on the Active SPME stage, while lighter compounds are allowed to continue to a cold Tenax® trap for quantitative recovery of C2 and heavier compounds. Water is eliminated using a direct vapor to solid deposition in a cold trap, thereby avoiding loss of water soluble polar compounds. System flows are controlled using Dean’s Switching rather than classical rotary valves, eliminating exposure to plastic rotors known to cause carryover and recovery issues. Data will be presented showing both the reproducibility and overall performance for EPA Method TO15 compounds, as well as the molecular weight extension provided by the Active SPME stage by comparing recoveries of a C10-C24 standard by direct GC injection verses preconcentration from commonly used 1.4L field sampling canister.
|Create Date||November 13, 2018|
|Last Updated||November 14, 2018|