Headspace gas chromatographic determination of distribution coefficients of selected organosulphur compounds and their dependence on some parameters

Using headspace gas chromatography, the distribution coefficients, Ki, of selected organosulphur compounds in air—water system as well as their temperature, ionic-strength and concentration dependences have been determined. Based on the i values, the detection limits for direct headspace gas chromatographic analysis with flame-ionization detection, aqueous solubilities and the Raoult-law activity coefficients have also been estimated. The detection limits were found to decrease with molecular weight within the homologous series studied. It is shown that an increase in the concentration of analytes in the gaseous phase can be most easily accomplished by elevating the temperature, the effect of ionic strength on the Ki values at 70°C was small. The dependence of the equilibrium gaseous-phase concentration on the liquid-phase concentration was found to be linear (with some exceptions) over the investigated concentration range (0.1–10 ppm). The detection limits were estimated to be in the 1–10-ppb range, thus indicating broad applicability of the direct headspace gas chromatographic analysis for organosulphur compounds. The values for the aqueous solubility and activity coefficients can be employed for physicochemical and environmental purposes.