Increasing the Sensitivity for 1,4-Dioxane Analysis in Drinking Water

Drinking Water
Oral Presentation

Prepared by J. Mayser1, N. Watson2, R. Cole1, R. Szafnauer1
1 - Markes International Ltd, Gwaun Elai Medi-Science Campus, Llantristant, No State Available, CF72 8XL, United Kingdom
2 - Markes International, Inc., 2355 Gold Meadow Way, Gold River, Gold River, Sacramento, CALIFORNIA, 95670, United States


Contact Information: [email protected]; 01443230935

ABSTRACT

In past water investigations at solvent release sites, 1,4-dioxane was typically not included as a target analyte because it was not detectable at low concentrations in a standard laboratory scan for volatile organic compounds. However, 1,4-dioxane has emerged as a likely human carcinogenic compound, and as it is highly soluble and does not readily biodegrade it tends to accumulate in the aquatic environment. Attitudes towards 1,4-dioxane have changed in recent years. This is reflected in the recent decrease of regulatory detection limits, in some cases to 25 ng/L (Bayerischer Landtag 17/16517).

Reliable low-level detection of 1,4-dioxane is challenging because of its high solubility, which makes it particularly difficult to extract from water. A combination of solid phase microextraction (SPME) with further preconcentration on a sub-ambient trap allows for multi-step enrichment (MSE), wherein analytes from multiple SPME extractions from a single sampling vial are concentrated on the trap prior to GC injection for analysis. With this technique 1,4-dioxane is removed from the headspace of the sample with each extraction, and time is then allowed for a new equilibrium to establish prior to the following extraction, dramatically improving extraction efficiency overall.

SPME-trap with MSE thus allows analysis of 1,4-dioxane at trace levels far surpassing what is possible with traditional SPME while maintaining peak shape, excellent linearity, low MDLs and highly reproducible results. SPME-trap with MSE is fully automated with Centri sample extraction and enrichment platform, avoiding highly manual sample preparation procedures associated with other techniques such as SPE. Furthermore, Centri allows for the re-collection and archiving of SPME extracts for later re-analysis if required. Here we demonstrate the fully automated extraction and enrichment of 1,4-dioxane at ng/L levels in water using a multi-phase (DVB/CAR/PDMS) fiber by SPME-trap with MSE on Centri.