The DBP exposome: Development of a new method to simultaneously quantify priority disinfection by-products and comprehensively identify unknowns. (1st January 2019)

• Record Type: Journal Article
• Authors: Kimura, Susana Y.; Cuthbertson, Amy A.; Byer, Jonathan D.; Richardson, Susan D.
• Is Part Of: Water research. Volume 148(2019)
• Page Start: 324
• Page End: 333
• Publication Date: 2019-01-01
• Subjects: DBPs -- Disinfection by-products -- Drinking water -- Non-target analysis -- Quantification; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.10.057
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Disinfected drinking water contains hundreds of disinfection by-products (DBPs) that are formed by the reaction of disinfectants with natural and anthropogenic organic matter, bromide, and iodide. Understanding what these DBPs are is important because millions of people worldwide consume drinking water every day, and human epidemiologic studies have reported cancer, miscarriage, and birth defects from consuming such waters. While more than 600 DBPs are reported in the literature, very few studies quantify complete classes of chlorinated, brominated, and iodinated DBPs. Also, very few studies conduct comprehensive non-target analyses of unknown DBPs to characterize the complete DBP exposure (the exposome). We developed a new gas chromatography (GC)-mass spectrometry (MS) method that simultaneously quantifies 39 priority unregulated DBPs from six different chemical classes (haloacetaldehydes, haloketones, haloacetamides, haloacetonitriles, halonitromethanes, and iodinated-trihalomethanes) and analyzes unknown DBPs with mass accuracy <600 ppm under full-scan conditions. Using a new type of time-of-flight (TOF) mass spectrometer, which combines selected ion monitoring (SIM)-level sensitivity with mass accuracy of ±0.05 Da, method detection limits of 3–61 ng/L were achieved. These levels were found to be quite comparable to those of a widely used single quadrupole mass spectrometer (2–90 ng/L) operated in SIM mode. However, analysis using this TOF mass spectrometer offers two additional advantages over traditional quadrupole-MS: (1) full-scan data, which provides additional confidence for target analytes, as well as complete mass spectra for unknown analysis, and (2) two decimal place mass accuracy, which allows additional confidence for target analytes and importantly, molecular formula indication for unknowns. High resolution accurate mass TOF was also used to validate identification of selected compounds. This new method was demonstrated on finished drinking waters from three different drinking water plants, where target quantification and non-target unknown analyses were performed simultaneously during the same run. This enabled the quantification of 39 DBPs, along with the non-target identification of many other drinking water contaminants, including two additional non-target DBPs: N, N -dimethylacetamide and N -nitrosodibutylamine. Graphical abstract: Highlights: New target and non-target GC-MS method that quantifies 6 different classes of DBPs. Non-target unknown analysis at two decimal place mass accuracy. Method detection limits between 3 and 67 ng/L for 39 priority unregulated DBPs. New method was demonstrated on chlorinated and chloraminated drinking water samples. Haloacetaldehydes were found to be the largest DBP class by weight of priority DBPs.