Membrane Extraction Combined with Thermodesorption/Gas Chromatography and Mass Selective Detection for the Analysis of Volatile Organic Compounds in Water

✍ Scribed by Hauser, Barbara ;Popp, Peter

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 108 KB
• Volume: 22
• Category: Article
• ISSN: 0935-6304
• DOI: 10.1002/(sici)1521-4168(19990401)22:4<205::aid-jhrc205>3.0.co;2-2

✦ Synopsis

The range of application of a commercial thermodesorption-cryofocussing unit connected to a gas chromatograph/mass selective detector was extended to water analysis by using it in conjunction with membrane extraction. A flow of nitrogen passes through a silicone hollow fiber immersed in the water sample and extracted volatile organic compounds are enriched in a sorption tube mounted on top of the extraction cell. The sorption tube is then placed in the thermodesorption unit and analyzed by GC/MS. The optimal extraction parameters of this combined method were found to be 30 min extraction at 20 8C with a stirring speed of 1,250 rpm and a flow rate of 100 mL/min nitrogen using a silicone hollow fiber of 0.3 m length. Under these conditions the reproducibility of the method was 5.2 -10.5% RSD. The linear dynamic range of the optimized method spans three orders of magnitude and detection limits were found to be 0.02 -0.1 lg/L for cis/trans-1,2-dichloroethene, benzene, trichloroethene, chlorobenzene, bromobenzene, ethylbenzene, 1,1,2,2-tetrachloroethane, and 1,2/1,4-dichlorobenzene. The method was found to be suitable for compounds with boiling points up to 220 8C as memory effects increased considerably from dichloro-to hexachlorobenzene. Highly contaminated groundwater samples were analyzed. Quantitative results corresponded well with those achieved with conventional headspace-GC/FID.