1,4-Dioxane is extensively used as an industrial solvent and a solvent stabilizer. It is also a by-product of manufacturing processes involving ethylene oxide. As a result, 1,4-dioxane is a widespread contaminant in both groundwater and surface water. Although 1,4-dioxane is classified as a probable human carcinogen with an excess one-in-a-million cancer risk level of 0.35 μg/L in drinking water, no federal drinking water standard exists for 1,4-dioxane. To improve exposure assessment and to evaluate the removal efficiency of treatment approaches, a rapid analytical method capable of quantifying aqueous 1,4-dioxane concentrations in the sub-μg/L range is needed.<br/> <br/>In this research, an analytical method for aqueous 1,4-dioxane concentrations was developed based on the EPA Method 522, which relies on solid phase extraction (SPE) for sample pre-concentration. As a less time- and labor-intensive alternative of sample preparation, a heated purge-and-trap (P&T) system was used instead of SPE. Aqueous samples are heated to 60°C during purging to increase recovery, and 1,4-dioxane is quantified by an isotope dilution method using mass-labeled 1,4-dioxane-d8 as the internal standard in gas chromatography/mass spectrometry (GC/MS). The method detection limit for this method is 56 ng/L, and the reporting range is 0.15-300 µg/L with highly reproducible results. With this method, recovery of 1,4-dioxane ranged from 85-110% in drinking water, surface water and wastewater effluent samples.<br/> <br/>The new P&T-GC/MS method was applied to investigate the occurrence and distribution of 1,4-dioxane in the Cape Fear River Watershed of North Carolina. Over 50 sampling points were strategically chosen to bracket possible sources. 1,4-Dioxane concentrations as high as 1,400 µg/L were found in streams downstream of municipal wastewater treatment plant discharges. Analysis of industries in the communities suggests that the plastics industry (PET products, thermoplastic, and plastics recycling) and the textile industry are possible sources.

Rapid and sensitive method for the determination of 1,4-dioxane analysis in a wide range of aqueous matrices

255th National Meeting (2018)

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