title: Vapor/Solid chemisorption model for passive sampling of aldehydes.
abstract: The vapor-phase chemisorption isotherms of valeraldehyde (n-valeraldehyde; 1-pentanal) and acrolein (2-propenal) above the critical face velocity (7.5 cm/s) were investigated at 25 degrees C and 36 percent relative humidity (RH) for a passive air sampling pellet of 10 percent O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA) on Tenax TA solid sorbent (80/100 mesh). A dynamic air dilution system with syringe pumps generated the vapor concentrations and humidity for the exposure chamber. The O-oxime derivatives were desorbed with hexane for gas chromatographic analysis on a nonpolar capillary column and electron capture detection. The pellet capacity was about 30 micromoles. Adsorption of valeraldehyde was best fitted by a Langmuir or Brunauer-Emmett-Teller (BET) I model. That for acrolein was described best by a Dubinin-Radushkevich model. A microporosity model explained why all the classical isotherms described the chemisorption behavior. An activated extrinsic precursor was suggested to facilitate the addition reaction by production of a protonated intermediate formed by the transfer of a proton to the aldehyde from an activated reaction site consisting of at least 2 PFBHA molecules.
authors.affiliation: Department of Environmental Health Sciences, UCLA Center for Occupational and Environmental Health, UCLA School of Public Health, Los Angeles, California, USA.
authors.forename: Shih-Wei
authors.initials: SW
authors.lastname: Tsai
authors.forename: Shane S Que
authors.initials: SS
authors.lastname: Hee
mesh_terms: D000327:Adsorption; D000395:Air Pollutants, Occupational / Q000032:analysis*; D000447:Aldehydes / Q000032:analysis* / Q000737:chemistry; D001273:Atmosphere Exposure Chambers; D007700:Kinetics; D016014:Linear Models
chemical_list: D000395:Air Pollutants, Occupational; D000447:Aldehydes