In-Tube Extraction of Volatile Organic Compounds from Aqueous Samples: An Economical Alternative to Purge and Trap Enrichment

A novel in-tube extraction device (ITEX 2) for headspace sampling was evaluated for GC/MS analysis of aqueous samples. Twenty compounds of regulatory and drinking water quality importance were analyzed, including halogenated hydrocarbons, BTEX compounds (benzene, toluene, ethylbenzene, xylenes), fuel oxygenates, geosmin, and 2-methylisobomeol. Five commercially available sorbent traps were compared for their compound specific extraction yield. On the basis of the results, a mixed bed trap was prepared and evaluated. The extraction parameters were optimized to yield maximum sensitivity within the time of a GC run, to avoid unnecessary downtime of the system. Method detection limits of 1-10 ng L-1 were achieved for volatile organic compounds (VOCs), which is much lower than demands by regulatory limit values. The performance of the ITEX system is similar to that of purge and trap systems, but it requires lower sample volumes and is less prone to contamination, much simpler, more flexible, and affordable. Average relative standard deviations below 10% were achieved for all analytes, and recoveries from spiked tap water samples were between 90% and 103%, mostly. The extraction is nonexhaustive, removing a fraction of 7% to 55% of the target compounds, depending on the air water partitioning coefficients. The method was also tested with nonsynthetic samples, including tap, pond, and reservoir water and different soft drinks.