Measurement & Monitoring: 32nd Quarterly Literature Update & Grant Survey

1,4-Dioxane: The Impact of Analytical Method -A Case Study Linton, P.J., J.C. Alonso, and T. Armstrong. Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2008). Battelle Press, Columbus, OH, ISBN 1­ 57477-163-9, Abstract G-005, 2008 Commercial laboratories commonly analyze for 1,4-dioxane in groundwater by either EPA Method 8260 or 8270, but Method 8260 generally does not achieve reporting limits that meet regulatory concentrations and 8270 does not list 1,4-dioxane as a reported analyte. Determination of 1,4-dioxane in water at low detection levels also can be accomplished using a modified approach to Method 8270 with isotope dilution. Because of time and sample volume concerns, many laboratories have begun analyzing for 1,4-dioxane using a modified Method 8260 with specific ion monitoring (SIM) GC-MS to improve the detection limits. During a recent characterization sampling at a central Florida site with groundwater impacted by chlorinated VOCs and 1,4-dioxane, split samples of groundwater were collected and analyzed by both Method 8270 and 8260 SIM. A significant difference was evident in reported concentrations of 1,4-dioxane by the two methods, sometimes by orders of magnitude. A study was initiated to evaluate the effect of the different analytical methods on reported concentrations. This paper presents an evaluation of the comparison of Method 8260 SIM, Method 8270, and Method 8270 with isotope dilution using native samples, multiple-level spike addition, and multipleconcentration laboratory control sample analysis to evaluate the overall accuracy and precision of the three methods. Isotope dilution was found to provide a correction factor that consistently provided a higher degree of accuracy and precision than the other methods. Subsequent evaluation of the addition of isotope dilution and a heated purge to the Method 8260 SIM analysis has been conducted by the State of Florida. The results of that evaluation have led Florida to specify the use of that method for all analyses of 1,4-dioxane in groundwater.