Measurement of aqueous solubility of hydrophobic volatile organic compounds by solute vapor absorption technique: Toluene, ethylbenzene, propylbenzene, and butylbenzene at temperatures from 273 K to 328 K

An apparatus and procedure are described for measuring the aqueous solubili ty of hydrophobic volatile compounds. The method employs the solute vapor a bsorption technique (SVA) for preparation of the saturated solution followe d by subsequent off-line HPLC analysis of the cosolvent adjusted aqueous so lution. The method circumvents several drawbacks encountered with the tradi tional liquid-liquid batch contacting ("shake-flask") system and yields rep roducible and precise results (3%). Correct performance of the method was d emonstrated using benzene as a test solute. Using the method, aqueous solub ilities of lower alkylbenzenes (toluene, ethylbenzene, propylbenzene, and b utylbenzene) were determined in the temperature range from 273 K to 328 K. The results are compared with available literature information. An excellen t agreement found for toluene gradually deteriorates for higher homologues, with the largest discrepancy occurring at the lowest temperatures. The lac k of reliable information for a decisive conclusion at subambient temperatu res appears to be rather general, calling for continued experimental effort .