The effects of adsorption on the reusability of Tedlar air sampling bags.

This study examined the adsorption and desorption behavior of six different organic compounds in Tedlar bags. Triplicate bags were filled with a gas mixture to yield concentrations of approximately 90 ppm of each analyte, then sampled and analyzed by capillary gas chromatography at predetermined intervals over a 3-week period. A first-order kinetic rate equation was fitted to the data, and measured rate coefficients for the six compounds ranged from zero for the nonadsorbing methyl tert-butyl ether to 0.09/day for the rapidly adsorbed methanol. Adsorptive losses of allyl alcohol, styrene, ethylbenzene, and propylene oxide were slower and less significant; rate coefficients ranged from 0.01 to 0.03/day. Following the adsorption phase of the study, the bags were put through a simple cleaning procedure consisting of N2-flushing and gentle heating steps. Analysis of variance was used to assess the effectiveness of each step. Five N2 flushes were adequate to remove residual methyl tert-butyl ether, allyl alcohol, and propylene oxide, but there seemed to be a degree of hysteresis for styrene and ethylbenzene. Combinations of flushing and heating also failed to remove all the styrene and ethylbenzene. Neither flushing nor heating removed any of the adsorbed methanol. Depending on the compound of concern, the reuse of Tedlar and other similar polyvinyl fluoride sample collection bags should be carefully considered before the start of any sampling program.