Potential of static sampling using solid-phase microextraction for the assessment of formaldehyde sorption on building materials

Formaldehyde is considered as a priority pollutant of indoor air due to its numerous indoor sources and health impact. Due to its physico-chemical properties, the interaction of gaseous formaldehyde with material surfaces is suspected to play an important role in the distribution and fate of this compound indoors. This paper proposes an experimental method providing several parameters characterizing the material/air exchanges for formaldehyde namely, the adsorption and desorption rate constants (kam and kdm) and the material/air equilibrium partition coefficient (Ke) and the initial gas-phase concentration in equilibrium with the material surface (Cieq0). These parameters are assessed in a closed system (glass cell) containing the material and by a static sampling using solid-phase microextraction (SPME) fibers for measuring gaseous concentrations at the material surface during the emission and adsorption phases. Compared to the available methods of determining these parameters described in the literature, this method has the following advantages: (1) Taking into account of sorption on the inner walls of cell in the calculation of the material sorption parameters; (2) An analytical solution assessing the adsorption and desorption rate constants simultaneously from data of the adsorption phase; (3) An assessment of these sorption parameters under experimental conditions close to those encountered in indoor environments; (4) a satisfying reproducibility of the measured sorption parameters. The main performance of SPME sampling was assessed. The applicability of this method was proven to compare the sorption behavior of formaldehyde towards floor coverings.