Identification and characterization of phenylacetonitrile as a nitrogenous disinfection byproduct derived from chlorination of phenylalanine in drinking water

Ma, Xiaoyan; Deng, Jing; Feng, Jiao; Shanaiah, Narasimhamurthy; Smiley, Elizabeth; Dietrich, Andrea M.

doi:10.1016/j.watres.2016.06.029

Cited by 42 publications

(7 citation statements)

References 53 publications

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“…The proposed formation pathways of HPAcAms during chlorination of phenylalanine could be proved reasonable from different aspects. First, among all of the five intermediates, I, III, and IV were already detected in previous studies, , and V was positively identified in the present study (Supporting Information Section S8 and Figure S7), which supported the proposed formation pathways. Second, the frontier electron densities (FEDs) of the highest occupied molecular orbital (HOMO) for phenylalanine were calculated using Gaussian 09 software at the B3LYP/3-21G* level (Supporting Information Figure S8), and the N atom in phenylalanine showed an overwhelmingly large 2FED 2 HOMO value (1.2321).…”

Section: Resultssupporting

confidence: 88%

Formation and Cytotoxicity of Halophenylacetamides: A New Group of Nitrogenous Aromatic Halogenated Disinfection Byproducts in Drinking Water

Kaw

Zhu

et al. 2022

Environ. Sci. Technol.

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Nitrogenous aromatic halogenated disinfection byproducts (DBPs) in drinking water have received considerable attention recently owing to their relatively high toxicity. In this study, a new group of nitrogenous aromatic halogenated disinfection byproducts, halophenylacetamides (HPAcAms), were successfully identified for the first time in both the laboratory experiments and realistic drinking water. The formation mechanism of HPAcAms during chlorination of phenylalanine in the presence of Br– and I–, occurrence frequencies, and concentrations in authentic drinking water were investigated, and a quantitative structure–activity relationship (QSAR) model was developed based on the acquired cytotoxicity data. The results demonstrated that HPAcAms could be formed from phenylalanine in chlorination via electrophilic substitution, decarboxylation, hydrochloric acid elimination, and hydrolysis. The HPAcAm yields from phenylalanine were significantly affected by contact time, pH, chlorine dose, and temperature. Nine HPAcAms with concentrations in the range of 0.02–1.54 ng/L were detected in authentic drinking water samples. Most tested HPAcAms showed significantly higher cytotoxicity compared with dichloroacetamide, which is the most abundant aliphatic haloacetamide DBP. The QSAR model demonstrated that the cellular uptake efficiency and the polarized distributions of electrons of HPAcAms play essential roles in their cytotoxicity mechanisms.

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Section: Resultssupporting

confidence: 88%

Formation and Cytotoxicity of Halophenylacetamides: A New Group of Nitrogenous Aromatic Halogenated Disinfection Byproducts in Drinking Water

Kaw

Zhu

et al. 2022

Environ. Sci. Technol.

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“…In chlorination, the formation of DCAN from PAN is negligible, as PAN is inert to chlorination (Figure S12). PAN has been previously reported to be very stable in chlorination, with a half lifetime of 792 h at 19 °C . However, PAN is readily degraded by UV/chlorine with first-order rate constants of 4.0 × 10 –4 to 9.2 × 10 –4 s –1 (Figure S13).…”

Section: Resultsmentioning

confidence: 99%

“…PAN has been previously reported to be very stable in chlorination, with a half lifetime of 792 h at 19 °C. 52 However, PAN is readily degraded by UV/chlorine with firstorder rate constants of 4.0 × 10 −4 to 9.2 × 10 −4 s −1 (Figure S13). The consumed PAN is partially converted to DCAN in UV/chlorine, with conversion rates of 14.2−25.6%.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Exploring Pathways and Mechanisms for Dichloroacetonitrile Formation from Typical Amino Compounds during UV/Chlorine Treatment

Hua

Zheng

et al. 2022

Environ. Sci. Technol.

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The formation of disinfection byproducts (DBPs) during UV/chlorine treatment, especially nitrogenous DBPs, is not well understood. This study investigated the formation mechanisms for dichloroacetonitrile (DCAN) from typical amino compounds during UV/chlorine treatment. Compared to chlorination, the yields of DCAN increase by 88–240% during UV/chlorine treatment from real waters, while the yields of DCAN from amino compounds increase by 3.3–5724 times. Amino compounds with electron-withdrawing side chains show much higher DCAN formation than those with electron-donating side chains. Phenylethylamine, l- phenylalanine, and l-phenylalanyl-l-phenylalanine were selected to represent amines, amino acids, and peptides, respectively, to investigate the formation pathways for DCAN during UV/chlorine treatment. First, chlorination of amines, amino acids, and peptides rapidly forms N-chloramines via chlorine substitution. Then, UV photolysis but not radicals promotes the transformation from N-chloramines to N-chloroaldimines and then to phenylacetonitrile, with yields of 5.4, 51.0, and 19.8% from chlorinated phenylethylamine, l-phenylalanine, and l-phenylalanyl-l-phenylalanine to phenylacetonitrile, respectively. Finally, phenylacetonitrile is transformed to DCAN with conversion ratios of 14.2–25.6%, which is attributed to radical oxidation, as indicated by scavenging experiments and density functional theory calculations. This study elucidates the pathways and mechanisms for DCAN formation from typical amino compounds during UV/chlorine treatment.

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“…Comparisons of the mass spectra and the GC retention times of these peaks with the corresponding data for commercially available chemical standards confirmed these assignments (data not shown). PAA (Hrudey et al 1988, Bruchet et al 1992, Froese et al 1999, Freuze et al 2005, Ma et al 2016, PAN , Freuze et al 2005, Ma et al 2016, and BC (Ma et al 2016) are reportedly produced during chlorination of phenylalanine. In contrast, CB, BA, and BN have not been reported to be TPs of phenylalanine, possibly because these compounds are produced in only very small amounts.…”

Section: Identification Of Tps In the Chlorinated Phenylalanine-contamentioning

confidence: 99%

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

et al. 2017

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Off-flavor in drinking water can be caused by transformation products (TPs) generated from organic compounds, such as amino acids, present during chlorination. However, the contributions of many of these TPs to overall off-flavor have not been quantified, mainly because the lack of appropriate chemical standards prevents sensory evaluation by means of a conventional flask test. In the present study, we used gas chromatography-mass spectrometry-olfactometry (GC-MS-O) to identify compounds responsible for the off-flavor generated by chlorination of an aqueous solution of the amino acid phenylalanine, and we propose a sensory evaluation procedure for quantification of the contributions of the identified TPs to the overall off-flavor, regardless of the availability of chemical standards of the TPs. GC-MS-O revealed that two TPs, N-chlorophenylacetaldimine and 2-chloro-2-phenylacetaldehyde, for which chemical standards are not commercially available, were the main components responsible for the off-flavor of the chlorinated solution. By using a sensory evaluation procedure involving a combination of GC-MS-O and a conventional flask test, we quantified the contributions of TPs to the overall off-flavor of the chlorinated solution. Approximately 60% of the off-flavor was attributable to free chlorine (13%), 2-chloro-2-phenylacetaldehyde (13%), trichloramine (12%) phenylacetaldehyde (11%) phenylacetonitrile (8%), and N-chlorophenylacetaldimine (2%). Treatment with powdered activated carbon (PAC) removed the off-flavor. Experiments with chlorination of N-labeled phenylalanine suggested that PAC reductively decomposed trichloramine into N gas and adsorbed all of the other identified TPs. Superfine PAC (median diameter, 0.7 μm) removed the off-flavor more rapidly than normal-size PAC (median diameter, 8.0 μm).

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Identification and characterization of phenylacetonitrile as a nitrogenous disinfection byproduct derived from chlorination of phenylalanine in drinking water

Cited by 42 publications

References 53 publications

Formation and Cytotoxicity of Halophenylacetamides: A New Group of Nitrogenous Aromatic Halogenated Disinfection Byproducts in Drinking Water

Formation and Cytotoxicity of Halophenylacetamides: A New Group of Nitrogenous Aromatic Halogenated Disinfection Byproducts in Drinking Water

Exploring Pathways and Mechanisms for Dichloroacetonitrile Formation from Typical Amino Compounds during UV/Chlorine Treatment

Use of gas chromatography–mass spectrometry–olfactometry and a conventional flask test to identify off-flavor compounds generated from phenylalanine during chlorination of drinking water

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