AWWA WQTC71563

The Orange County Water District (OCWD) has monitored eight nitrosamines and other emerging contaminants within its advanced water treatment plant and monitoring facilities at sub-parts per trillion levels. To effectively monitor for these critical targets, OCWD has improved specific analytical methods using automated solid phase extraction processes. Since the molecular weight, polarity and chemical stability of these compounds represent a wide range of conditions, the extraction and concentration of these compounds from the treated wastewater requires very specific optimization of the solid phase extraction techniques. Sample flow rate, elution time, drying time, and nitrogen gas flow rate are all key operational parameters within the extraction process. The OCWD laboratory has successfully improved the method to determine these targets at parts per trillion levels for eight specific nitrosamines, including nitrosomorpholine, which is not listed in U.S. Environmental Protection Agency (USEPA) Method 521, 1,4-dioxane, and other critical target compounds. This paper presents improved method techniques and analytical results derived from the automated solid phase extraction process, using carbon and polymer based sorbents and optimized operating conditions. Includes 11 references, tables, figures.