Characterization of Photothermal Desorption-Compatible Diffusive Samplers for Volatile Organic Compounds

Products and startingmaterials containing volatile organic compounds(VOCs) can easily be found in a variety of businesses, making thema common source of occupational exposure. To prevent negative impactson employee health, field industrial hygienists must conduct regularsampling to ensure exposures remain below the regulatory limits setby governmental and professional associations. As such, the need forsensitive and reliable exposure assessment techniques becomes evident.Over the preceding decade, the industrial hygiene research group atthe University of Alabama at Birmingham (UAB) has been working onthe development of an emerging, preanalytical technique known as photothermaldesorption (PTD) to improve upon the analytical sensitivity of currentlyemployed methods. PTD's novel design uses pulses of high-energylight to desorb analytes from thermally conductive, carbonaceous sorbents,to be delivered to downstream analytical detectors. Since PTD'sconception, the theoretical framework and advances in sorbent fabricationhave been investigated; however, further work is needed to producea field-ready sampling device for use with PTD. As such, objectivesof the present work were to design a PTD-compatible diffusive samplerprototype and characterize the prototype's sampling efficienciesfor toluene, n-hexane, trichloroethylene, and isopropylalcohol. In pursuit of these objectives, the study empirically quantifiedthe sampled masses of toluene, n-hexane, trichloroethylene,and isopropyl alcohol, at occupationally relevant air concentrations,to be 12.17 & PLUSMN; 0.06, 8.2 & PLUSMN; 0.1, 3.97 & PLUSMN; 0.06, and 8.0 & PLUSMN; 0.1 mg, respectively. Moreover, the analyte sampling efficiencieswere found to be 2.2 & PLUSMN; 0.1, 1.7 & PLUSMN; 0.1, 1.2 & PLUSMN; 0.1, and0.51 & PLUSMN; 0.05 (unitless) when comparing empirically (i.e., laboratoryobserved) sample mass values to theoretically predicted values. Thesampling efficiencies and collected sample masses reported hereindemonstrate the promising design of PTD-compatible diffusive samplers.When used in conjunction with the PTD method, the prototype samplerspresent strong evidence for improving analytical sensitivity in exposureassessments of VOCs in the workplace.