A malodorous chemical, 2-ethyl-5,5′-dimethyl-1,3-dioxane (2EDD) created a drinking water taste and odor episode in Pennsylvania (USA) during 1992. The odor episode occurred as the result of a reaction between propionaldehyde and neopentyl glycol in the waste tank of a resin manufacturer. Samples of this waste water were extracted and analyzed. An in situ aqueous preparation of 2EDD was completed to demonstrate that 2EDD could have formed under the conditions found in the waste water. The stability (fate) of 2EDD was studied at different aqueous pHs (pH3, 5, 7, and 9). Some hydrolysis of 2EDD was found at pHs<7 after one week, but 2EDD appeared to be stable at pH 9. The odor characteristics and odor threshold of 2EDD were determined by the method of flavor profile analysis. The odor threshold concentration of 2EDD was found to be between 5 and 10 ng/l and was described as having a sweet, tutti fruitti odor (near the odor threshold concentration) and a burnt, sickening sweet odor at higher concentrations. This study also discovered that slight antagonism in chloraminated drinking water may occur at or near the threshold odor level of 2EDD.

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