Determination of Trace Hydrophobic Volatiles in Aqueous Media by a Technique of Multiple Stripping and Trapping in a Closed Circuit

The double-sampling method of quantitative headspace-gas analysis was assayed by analysing model water-gas systems with benzene, toluene, ethylbenzene, n-decane, and n-dodecane as analytes. With this method, two headspace samples are withdrawn successively from the system and analysed by gas chromatography. The total initial contents of the analytes in the system are calculated by virtue of the decrease in their concentrations in the gaseous phase, brought about by the withdrawal of the first headspace sample. Combined with Grob's closed-loop strip/trap technique, the method provides for the determination of ppb (10 9 ) concentrations of the above hydrocarbons in water with an average relative error of several percent.