Characterizing the equilibrium relationship between DEHP in PVC flooring and air using a closed-chamber SPME method

• A closed-chamber SPME method to characterize emission of DEHP from PVC flooring.
• Artifact from wall-loss of sampling lines and of thermal desorption system avoided.
• y0 is smaller than saturated vapor pressure (Psat) of DEHP.
• y0/Psat increases little as mass fraction of DEHP increases as reporting before.
• Error-analysis-based suggestion is given to improve precision and time efficiency.

The di-(2-ethylhexyl) phthalate (DEHP) concentration in the air immediately adjacent to a polyvinyl chloride (PVC) flooring surface, y0 (μg/m3), has been identified as one of the critical parameters governing the emission process and consequent exposure. At room temperature and below, the relationship between y0 and the vapor pressure of pure DEHP (Psat) is still unclear. Few studies have been conducted to examine the influence of the mass fraction of DEHP in PVC on the relationship. In this study a new closed-chamber solid phase microextraction (SPME) method is developed to characterize ratio of y0 to Psat at 23 °C. This method avoids the artifact from wall-loss of sampling lines and of the thermal desorption system, in contrast to ventilated-chamber methods. Results show that at 23 °C y0 is significantly lower than the vapor pressure of pure DEHP. When the mass fraction of DEHP in PVC flooring increases from 13% to 23%, y0/Psat is increased by 7.2%, similar to what is reported in the literature. The sorption capacity of SPME stainless steel (SS) rods differs by up to 104%, although they are all made of SS. Based on error analysis, strategies are recommended to improve the precision and time efficiency. The method developed here should work for other SVOC-polymer systems.