Analysis of haloacetamides and effect of excess nitrogen on haloacetamide formation during chloramination of acetaminophen

• Main Authors: Jhih-Yun Jhang, 張芷昀
• Other Authors: Wei-Hsiang Chen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/b8yv9y

碩士 === 國立中山大學 === 環境工程研究所 === 107 === While chlorination has been used worldwide for drinking water disinfection, the disinfection byproducts (DBPs) causes the concern of health risk. Haloacetamides (HAcAms), as emerging nitrogen-containing disinfection byproducts (nitrogenous DBPs, N-DBPs), possess higher cytotoxicity and genotoxicity than regulated haloacetic acids and halonitromethanes. Studies have shown that HAcAms are formed during chlorination and oxidation of specific pharmaceuticals. There are two purposes of this study. One is to establish a method based on salting-out-assisted liquid-liquid extraction followed by gas chromatography-mass spectrometry for determination and quantification of HAcAms-like compounds. By adding 3 mL of methyl tert-butyl ether (MtBE) to the sample (50 mL), HAcAms in the sample were extracted by shaking vigorously for two minutes, followed by collection of the compounds in MtBE extract. The foregoing was repeated and the combined extracts were concentrated to 0.5 mL by nitrogen blowdown. The extract (2 μL) was injected in splitless mode, with a inlet temperature of 180°C. The analytes were separated by using the DB-1701 column. The oven temperature was programmed as follows: initial temperature of 40°C and hold 3 minutes, raised to 200 °C at 15°C/min then hold 2 minutes, then controlled at 250 °C at 30 °C/min. The overall detection time was 18.33 minutes. The method detection limit (MDL) of chlorohaloacetamide, monobromohalide, dichlorohaloacetamide, monochloroammonium bromide, and trichlorohaloacetamide were 4.84, 9.71, 66.6, 67.41, and 86.9 μg/L respectively, which could be further imporved by adjusting the concentration ratio. The other objective of the study is to explore the formation of HAcAms possibly affected by the excess nitrogen source during chloramination of acetaminophen, a widely used drug in Taiwan. The formation of HAcAms were affected by four critical factors including acetaminophen, chloramine, ammonia, and an acidic pH condition, as the absence of anyone alleviated the HAcAms formaiton. Although it is known that halogen and nitrogen supplies are ciritcal for the formation of HAcAms, our results demonstrated the sufficient chloramine for reactions of HAcAm formation from acetaminophen was more important that the amount of nitrogen needed (i.e., the chlorine consumption could be more than two orders of magnitude higher than that of nitrogen). Sufficient oxidant such as chloramine seems to be indispensable to react with acetaminophen and to initiate the formation of HAcAms since acetaminophen plays an important nitrogen source. This research provides not only an analytical method for the following HAcAms studies but also an insight into possible correlation between nitrogen pollution, which is increasingly typical in the environment, and the formation of emergent N-DBPs.