Solid-phase dynamic extraction for the enrichment of polar volatile organic compounds from water

Abstract

Headspace solid-phase dynamic extraction coupled to gas chromatography–mass spectrometry (HS-SPDE-GC/MS) was evaluated for the trace determination of polar volatile organic compounds (PVOC) from aqueous matrices. The target compounds included 3 ethers and 12 alcohols. Four SPDE needle coatings with different phase polarities and sorption properties (WAX, 1701, PDMS, PDMS/AC) were tested. The effects of extraction temperature, number of extraction cycles, and ionic strength on partitioning of the target compounds have been investigated in detail, including the determination of salting-out constants for the investigated compounds. Lowest method detection limits (MDLs) were obtained with the WAX and the PDMS/AC phase. The WAX phase showed MDLs for ethers in the range of 0.06 μg/L (MTBE) to 0.8 μg/L (1,4-dioxane) and for alcohols between 0.02 μg/L (3-methyl-1-pentanol) and 3.5 μg/L (1-propanol). The evaluated MDLs for ethers with the PDMS/AC were in the range 0.06 μg/L (MTBE) to 1.2 μg/L (1,4-dioxane) and for alcohols between 0.004 μg/L (1-hexanol) and 4.9 μg/L (ethanol). Using either of these two phases, SPDE provides comparable or better sensitivities for the investigated compounds than other enrichment techniques, high sample throughput because of full automation, and short extraction times as well as a high robustness of the extraction phase because of its protection inside the steel needle. SPDE applicability has been demonstrated for the determination of fusel oils in different alcoholic beverages.