Determination of the Henryʹs law constant for dimethyl sulfide in seawater

This study describes a modified method to measure the Henryʹs law constant (Hc) of dimethyl sulfide (DMS) across air-water interface. A fixed amount of DMS was added into a 50 ml gas-tight glass syringe with air-water (seawater or distilled water) and equilibrated twice with different volumes of air but identical volume of water. The He of DMS in water could be determined by measuring the concentrations of DMS in the air phases of two equilibrium by gas chromtography. The He of DMS in seawater and distilled water determined by the modified method at 18°C were 0.069 and 0.056, respectively, and the relative standard deviation was less than 5%. The modified method was used to determine the effects of temperature on He of DMS in seawater and concentration of NaCl on He of DMS in freshwater.