| Semivolatile organic compounds (SOCs) partition mass between gas and particle phases in the atmosphere. The fate and transport of SOCs in the environment largely depends on this partitioning. The objective of this research was to (a) develop and characterize a method for measuring gas-particle (G/P) partitioning ratios of SOCs, (b) compare the method to existing techniques, (c) characterize the effects of various sampling biases, and (d) develop theory to predict SOC uptake by the human lung.; Objective A was completed with laboratory tests of an electrostatic precipitator (ESP). Measurements of G/P partitioning ratios are biased if the collection efficiency for either particles or gases is less than 100%, if some particle-phase mass is measured erroneously as gas-phase (adsorption), or if some gas-phase mass is measured erroneously as particle-phase (evaporation). ESPs collect particles with high efficiency and reduce adsorptive and evaporative artifacts without substantially perturbing the G/P equilibrium. Adsorption and evaporation artifacts were 5–100 and 2.3 times lower, respectively, in an ESP compared to a filter sampler. However, the ESP corona can cause chemical artifacts to the sampled aerosol. Ozone generated by the corona oxidizes reactive gas-phase SOCs, whereas corona ions react with collected particles. ESPs can measure more persistent SOCs accurately (alkanes and PAHs), however, sampling of reactive compounds (alkenes) is inappropriate.; Equations (objective C) to predict measurement errors were developed from chamber test data (objective B) with four methods: ESP, filter, filter-filter, and denuder. Filter samplers are susceptible to adsorption, whereas filter-filter samplers may be biased by both adsorption and evaporation. The ESP sampler can introduce small biases from chemical artifacts at low concentrations, non-ideal particle collection, and evaporative losses. The denuder sampler measures G/P partitioning accurately when particle losses in the denuder and gas breakthrough are negligible.; A dimensionless deposition number, D, developed from partitioning theory, (objective D) indicates whether particles or gases are most responsible for SOC deposition in the lungs. The deposition number allows industrial hygienists to design effective strategies to minimize risks associated with exposure to SOCs. |
