Measurement of the Henry's constant of dimethyl selenide as a function of temperature

The Henry's constant (K-h) represents the equilibrium partitioning of a gas eous compound between the vapor and liquid phases, and therefore is an impo rtant parameter describing the mobility of the compound in soil. Using the method of headspace analysis, we determined the K-h Of dimethyl selenide (D MSe) at temperatures ranging from 4 to 40 degrees C. The K-h value was deri ved by regression analysis of the liquid phase concentration observed at va rious liquid volumes based on mass balance. The dimensionless K-h Of DMSe r anged from 0.032 to 0.135, corresponding to a liquid concentration that is 7 to 31 times higher than the vapor concentration. The nonlinear regression equation describing the dependence of K-h On temperature (T, degrees C) is K-h = 0.0248exp (0.0418T), indicating that a higher temperature favors par titioning of DMSe to the vapor phase and thus increases transport of DMSe f rom soil to the atmosphere.