Haloquinone Chloroimides as Toxic Disinfection Byproducts Identified in Drinking Water

Abstract

Haloquinone chloroimides (HQCs) are suspected to be highly toxic contaminants, and their production during drinking water disinfection is predicted. However, HQC disinfection byproducts (DBPs) have not been reported in drinking water to date because of analytical limitations. In this study, we developed an analytical method to detect five HQCs, including 2,6-dichloroquinone-4-chloroimide (2,6-DCQC), 2,6-dibromoquinone-4-chloroimide (2,6-DBQC), 2-chloroquinone-4-chloroimide (2-CQC), 3-chloroquinone-4-chloroimide (3-CQC), and 2,6-dichloroquinone-3-methyl-chloroimide (2,6-DCMQC). This method combined a derivatization reaction of HQCs with phenol in alkaline solutions to produce halogenated indophenols, a solid-phase extraction pretreatment using hydrophilic–lipophilic balanced (HLB) cartridges, and a multiple reaction monitoring (MRM) method for quantification. The method was demonstrated to be sensitive and accurate with recoveries of 71–85% and limits of detection of 0.1–0.2 ng/L for the five tested HQCs. Using this method, five tested HQCs were identified in drinking water samples from nine water treatment plants and water distribution systems as new DBPs at concentrations of up to 23.1 ng/L. The cytotoxicity of the five tested HQCs in HepG2 cells was higher than or comparable to that of 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), an emerging DBP that was hundreds to thousands of times more toxic than regulated DBPs. This study presents the first analytical method for HQC DBPs in drinking water and the first set of occurrence and cytotoxicity data of HQC DBPs.

Revisiting Disinfection Byproducts with Supercritical Fluid Chromatography-High Resolution-Mass Spectrometry: Identification of Novel Halogenated Sulfonic Acids in Disinfected Drinking Water

“…The structures of 13 C 2 -15 N labeled ClANSA and Cl 2 ANSA, as well as 13 C 2 labeled Cl 2 AcAlSA, were confirmed by NMR spectroscopy (Figure S23, Table S2, and Text S1). Furthermore, their concentrations in this DBP mixture were estimated using 13 Curea as the internal quantification standard (i.e., 549 μM, 391 μM, 139 μM for 13 C 2 -15 N-ClANSA, 13 C 2 -15 N-Cl 2 ANSA, and 13 C 2 -Cl 2 AcAlSA, respectively, Table S3 and Text S2). The low intensities of other chlorinated analogues did not allow their accurate identification and quantification.…”

“…The structures of the 13 C 2 - 15 N labeled mono-and dichloroacetonitrilesulfonic acids (ClANSA and Cl 2 ANSA) and the 13 C 2 labeled dichloroacetaldehydesulfonic acid (Cl 2 AcAlSA) were further confirmed by their respective chemical shifts ( 1 H, 13 C, and 15 N NMR spectra) and 2D NMR correlation spectra. Their concentrations were estimated based on their relative abundances to 13 C-urea (used as the internal quantification standard) in 13 C NMR spectra. Another aliquot (10 μL) of this extract was used to make a serial dilution in acetonitrile and water (9:1, v:v).…”

“…For NMR analyses, an aliquot (230 μL) of this extract was spiked with 100 μL of 13 C-urea (4.23 mM) and 2 mg of Cr(acac) 3 . The 100 MHz 13 C NMR spectra were recorded using a 400 MHz Bruker AVIII HD spectrometer with a 30°flip angle and a repetition delay of 35 s ( 1 H decoupling only during acquisition, pulse sequence: zgig30). The structures of the 13 C 2 - 15 N labeled mono-and dichloroacetonitrilesulfonic acids (ClANSA and Cl 2 ANSA) and the 13 C 2 labeled dichloroacetaldehydesulfonic acid (Cl 2 AcAlSA) were further confirmed by their respective chemical shifts ( 1 H, 13 C, and 15 N NMR spectra) and 2D NMR correlation spectra.…”

“…The 100 MHz 13 C NMR spectra were recorded using a 400 MHz Bruker AVIII HD spectrometer with a 30°flip angle and a repetition delay of 35 s ( 1 H decoupling only during acquisition, pulse sequence: zgig30). The structures of the 13 C 2 - 15 N labeled mono-and dichloroacetonitrilesulfonic acids (ClANSA and Cl 2 ANSA) and the 13 C 2 labeled dichloroacetaldehydesulfonic acid (Cl 2 AcAlSA) were further confirmed by their respective chemical shifts ( 1 H, 13 C, and 15 N NMR spectra) and 2D NMR correlation spectra. Their concentrations were estimated based on their relative abundances to 13 C-urea (used as the internal quantification standard) in 13 C NMR spectra.…”

“…Moreover, the water samples from DWTPs 1 and 2 prior to disinfection were spiked with various amounts of this mixture and analyzed using SFC-QTOF following freeze-drying. No clear trend was observed on the apparent recovery rates of 13 C 2 -15 N-ClANSA, 13 C 2 -15 N-Cl 2 ANSA, and 13 C 2 -Cl 2 AcAlSA depending on the water matrix or spiked concentrations (Figure S24). Good recovery was obtained for HANSA analogues (i.e., average apparent recovery rate of 100 ± 10% for 13 C 2 -15 N-ClANSA and 99 ± 7% for 13 C 2 -15 N-Cl 2 ANSA), whereas 13 C 2 -Cl 2 AcAlSA was incompletely recovered (43 ± 10%).…”