A new solution for the passive monitoring of Volatile compounds to sub-PPB levels in air is presented. New adsorbent based sampling devices called SorbentTM Pens are used to passively collect air samples for 24 hours to 2 weeks, depending on the sensitivity and period of time weighted averaging desired. For this study, Carbopack X was used to specifically target BTEX compounds, although the adsorbent can be changed to recover lighter compounds such as Vinyl Chloride and Chloromethane, or much heavier compounds into the Semi-Volatiles range. A novel Sorbent Pen thermal desorption unit is introduced that rapidly transfers the collected sample directly into a GC, eliminating the need for a secondary focusing trap. Direct GCMS sample introduction results in far less carryover and system contamination than those solutions that perform secondary trapping and then transfer through long, heated lines to the GC. A pre-column inside the GC oven is used to backflush and eliminate heavier compounds that would otherwise contaminate the primary GC column, thereby reducing GC bakeout times. Data showing a calibration curve from 0.3 PPBv to 15 PPBv is presented, along with analytical precision when collecting duplicate and triplicate Sorbent Pens during a 1 week sampling period. Comparison were made to co-located 1 week sampling into two SiloniteTM coated, 6L stainless steel canisters to prove the accuracy of the technique and to validate sample collection rates for BTEX compounds.
|Create Date||May 24, 2017|
|Last Updated||July 13, 2017|