Analyte Recovery of Volatile Organic Compounds: A Passive Sampling Analysis via Photothermal Desorption Compatible Diffusive Samplers

Volatile organic compounds (VOCs) are common sources of occupational exposure throughout a variety of industries. To protect personnel from overexposure, field industrial hygienists must conduct compliance sampling. In efforts to improve upon analytical sensitivity and time-to-knowledge of existing VOC exposure assessment methods, the industrial hygiene research group at UAB has developed a preanalytical technique known as photothermal desorption (PTD), which uses pulses of high-energy light to desorb analytes from thermally conductive, carbonaceous sorbents. To-date, the theoretical and conceptual groundwork for PTD have been laid, and advances have been made toward a first-generation, PTD-compatible diffusive sampler. However, additional characterizations of the prototype sampler's performance are needed before the method is ready for in-field deployment. As such, the objectives of this study were 2-fold: (1) the primary objective was to determine the percent mass recovered via PTD of samples collected for various VOC analytes (i.e., toluene, <i>n</i>-hexane, isopropyl alcohol, and trichloroethylene), and (2) the secondary objective was to quantify the analyte adsorption capacities of buckypaper (BP) sorbents for each VOC of interest. The percent mass recovery of toluene, <i>n</i>-hexane, trichloroethylene, and isopropyl alcohol were found to be 0.60 ± 0.09, 1.2 ± 0.09, 1.1 ± 0.1, and 14.0 ± 1.0% per PTD pulse, and analyte adsorption capacities for BP sorbents were determined to be 152 ± 5 mg/g at 219 ppm toluene, 75 ± 42 mg/g at 292 ppm <i>n</i>-hexane, 104 ± 37 mg/g at 101 ppm trichloroethylene, and 105 ± 19 mg/g at 413 ppm isopropyl alcohol. The observed differences in desorption of analytes are likely attributed to varying types of weak intermolecular forces acting on aromatic rings, aliphatic chains, and polar moieties. While the large standard deviations in adsorption capacities may be explained by nonuniformity of nanotube alignment in respective sorbents. The early stage, prototype characterization data presented in this study, demonstrates the promising nature of PTD used with passive air samplers and provides a solid foundation for future development of the preanalytical technique and accompanying sampling devices.