Development of measurement method for estimating gas-phase concentration of SVOCs in equilibrium with the source material surface at any temperature

Semi-volatile organic compounds (SVOCs) are ubiquitous toxic indoor pollutants. The gas-phase concentration in equilibrium with the material surface (y₀) is the key parameter to estimate their emissions from indoor materials. The Clausius-Clapeyron relationship was used to determine y₀ at 25 °C of phthalates (DnOP and DiNP), organophosphate (OP) esters (TCPP, TDCPP, TPP and EHDPP) and DINCH emitted by vinyl floorings (VF), polyvinyl chloride (PVC)-coated fabrics and polyurethane (PU) cushioning foam. These materials were placed in a Micro-Chamber/Thermal Extractor (M-CTE, MARKES) and the gas-phase concentrations were measured at several elevated temperatures (T). y₀ was estimated at each temperature and the empiric relationship between y₀ and T was established. The extrapolated y₀ values were compared to experimental values at 25 °C. The influence of the temperatures used and the position of the material in the cell were investigated. The results indicate that y₀ at 25 °C are very low, mostly below 1 μg m⁻³. While for DiNP, TCPP, TDCPP and DINCH, the results are of the same order of magnitude as those available in the literature, y₀ of DnOP, TPP and EHDPP are reported for the first time. The temperatures used had an impact on the extrapolated y₀, but the consequences should be limited due to low values. Upon lifting the materials in the cell, the steady state gas phase concentration was close to y₀. This configuration can be used for quick y₀ estimation. The benefit of this method is the ability to estimate y₀ at any temperature which is useful to estimate exposure under different scenarios.