AWWA WQTC59002

The California Department of Health Services (CADHS) sets the reportable detection limits at 5 parts per trillion for 1,2,3-trichloropropane and 3 parts per billion for 1,4- dioxane. Due to the demand of low-level detection limit and poor purging efficiency of these compounds, the existing purge and trap techniques and instrumentation could not meet the detection requirements set by CADHS. The available liquid-liquid extraction method requires a 1L sample, 200 ml of organic solvents, and 16 hours of reaction to extract these compounds from water matrix. The Orange County Water District (OCWD) has developed a very reliable and sensitive method without using any organic solvents and manual labor for a sample extraction. Since 1,2,3-trichloropropane and 1,4-dioxane both are very water-soluble and volatile, the improved purge and trap techniques could separate these compounds. 20 minutes of purging with 40 ml/min of helium and 15 minutes of baking at 260 C for trap increased the purging efficiency more than 2 times. Also, the interested ions are further retrieved by multiple mass spectrometry technology, which improved the sensitivity of the system more than 50 times than normal mass spectrometry. The retention time of 1,2,3-trichloropropane is 26.4 min and 17.1 min for 1,4-dioxane. The method detection limits of 1,2,3-trichloropropane and 1,4- dioxane based on 25 ml of the sample volume are reported as 1.4 parts per trillion and 0.1 parts per billion, respectively. The improved purge and trap techniques using multiple mass spectrometry could save 90% of extraction time and 100% of solvent consumption compared to the continuous liquid-liquid extraction technique without sacrificing these detection limits and reliability of the analysis. The developed techniques have been successfully applied to monitor groundwater contamination and increase the removal efficiency of these compounds by wastewater treatment facility using microfiltration and ultraviolet irradiation. Includes 12 references, tables.