1,4 dioxane – sometimes referred to as just dioxane – has gotten a lot of press since the U.S. EPA added it to the third Unregulated Contaminant Monitoring Rule (UCMR 3). It is a relatively common solvent in analytical laboratories; however, it also finds use as a stabilizer for manufacturing items such as shampoo, cosmetics and food additives. After the EPA deemed this compound “likely to be carcinogenic to humans” and found it in a number of groundwater sources across the U.S., 1,4 dioxane was added to the UCMR 3 list and is now a regulated, routinely monitored contaminant.
This compound can be extracted from water using a number of different techniques; however, it’s highly soluble in water and is relatively volatile. These properties make it challenging to recover without loss due to volatilization. Purge and trap approaches use an inert gas to volatilize contaminants, which eliminate losses due to heating. Unfortunately, its effectiveness is severely limited for highly soluble compounds such as 1,4 dioxane. Continuous liquid-liquid extraction (CLLE) is also used for these types of extractions; however, a huge amount of solvent is required to complete the extraction – all of which must be concentrated down before analysis.
To address these challenges, the EPA developed Method 522 which uses a solid phase extraction cartridge. This approach solves the challenges of heating losses and uses minimal solvent which reduces concentration. This type of extraction was presented at the recent National Environmental Monitoring Conference (NEMC) in New Orleans. The presentation, which included details on the extraction process and results to demonstrate compliance with EPA Method 522, can be found here.
What are the challenges you face when performing your extractions of 1,4 dioxane? Highlight them in the comments below!