Time integrated sampling of TO14 compounds into stainless steel canisters was evaluated under a variety of conditions. Four different flow controllers were tested at temperatures ranging from 4 deg. C to 40 deg. C to determine how well they maintained a constant flow rate despite changes in ambient temperatures. The three flow controllers with fixed restrictors maintained a relatively constant flow rate over the temperatures tested, while the flow controller with a variable flow restrictor showed an increase in flow of 1300% as the temperature was raised from 4-40 deg. C. The effect water has on recovery was also studied by sampling under dry conditions (RH=10%) and more normal conditions (RH=50%).
Finally, individual parts that make up a passive canister sampler were evaluated to determine how each affects the recovery of TO14 analytes. Recoveries increased as flow path cleanliness improved and adsorptive surfaces were eliminated. The greatest improvements in recovery were obtained by electropolishing the inside of inlet tubing, and by replacing the 2um stainless steel inlet filter with a deactivated glass frit.
|Create Date||September 25, 2015|
|Last Updated||September 18, 2018|