Trace Analysis of 61 Emerging Br-, Cl-, and I-DBPs: New Methods to Achieve Part-Per-Trillion Quantification in Drinking Water

166

Although >700 disinfection byproducts (DBPs) have been identified, >50% of the total organic halogen (TOX) in drinking water chlorination is unknown, and the DBPs responsible for the chlorination-associated health risks remain largely unclear. Recent studies have revealed numerous aromatic halo-DBPs, which generally present substantially higher developmental toxicity than aliphatic halo-DBPs. This raises a fascinating and important question: how much of the TOX and developmental toxicity of chlorinated drinking water can be attributed to aromatic halo-DBPs? In this study, an effective approach with ultraperformance liquid chromatography was developed to separate the DBP mixture (from chlorination of bromide-rich raw water) into aliphatic and aromatic fractions, which were then characterized for their TOX and developmental toxicity. For chlorine contact times of 0.25−72 h, aromatic fractions accounted for 49−67% of the TOX in the obtained aliphatic and aromatic fractions, which were equivalent to 26−36% of the TOX in the original chlorinated water samples. Aromatic halo-DBP fractions were more developmentally toxic than the corresponding aliphatic fractions, and the overall developmental toxicity of chlorinated water samples was dominated by aromatic halo-DBP fractions. This might be explained by the considerably higher potentials of aromatic halo-DBPs to bioconcentrate and then generate reactive oxygen species in the organism.

Section: Resultsmentioning

confidence: 99%

Section: Materials and Methodsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

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How Much of the Total Organic Halogen and Developmental Toxicity of Chlorinated Drinking Water Might Be Attributed to Aromatic Halogenated DBPs?

Han

Zhang

Jiang

et al. 2021

166

“…To date, more than 700 DBPs have been identified in drinking water, and many are cytotoxic, genotoxic, mutagenic, or carcinogenic. , Among these compounds, iodo-THMs (I-THMs), iodoacetic acids (IAAs), haloacetonitriles (HANs), haloacetaldehydes (HALs), halonitromethanes (HNMs), haloacetamides (HAMs), and haloketones (HKs) are considered as priority DBPs, owing to their detection frequency, concentrations, and toxicities. − Compared to regulated THMs and haloacetic acids (HAAs), most of these unregulated priority DBPs are much more cytotoxic and genotoxic. ,− However, there is little information on the occurrence and formation of DBPs in tea, with only one paper reporting one class of DBPs (THMs) in tea brewed using real tap water …”

Section: Introductionmentioning

confidence: 99%

Are Disinfection Byproducts (DBPs) Formed in My Cup of Tea? Regulated, Priority, and Unknown DBPs

Aziz

Granger

et al. 2021

Self Cite

Globally, tea is the second most consumed nonalcoholic beverage next to drinking water and is an important pathway of disinfection byproduct (DBP) exposure. When boiled tap water is used to brew tea, residual chlorine can produce DBPs by the reaction of chlorine with tea compounds. In this study, 60 regulated and priority DBPs were measured in Twinings green tea, Earl Grey tea, and Lipton tea that was brewed using tap water or simulated tap water (nanopure water with chlorine). In many cases, measured DBP levels in tea were lower than in the tap water itself due to volatilization and sorption onto tea leaves. DBPs formed by the reaction of residual chlorine with tea precursors contributed ∼12% of total DBPs in real tap water brewed tea, with the remaining 88% introduced by the tap water itself. Of that 12%, dichloroacetic acid, trichloroacetic acid, and chloroform were the only contributing DBPs. Total organic halogen in tea nearly doubled relative to tap water, with 96% of the halogenated DBPs unknown. Much of this unknown total organic halogen (TOX) may be high-molecular-weight haloaromatic compounds, formed by the reaction of chlorine with polyphenols present in tea leaves. The identification of 15 haloaromatic DBPs using gas chromatography− high-resolution mass spectrometry indicates that this may be the case. Further studies on the identity and formation of these aromatic DBPs should be conducted since haloaromatic DBPs can have significant toxicity.

“…Each SPE cartridge was conditioned using 10 mL of MtBE or EtOAc followed by 10 mL of methanol and then equilibrated using ≥10 mL of DI water. Prior to the extraction, the NaHCO 3 solution spiked with test compounds was acidified to pH ∼3.7 using H 2 SO 4 ; this pH value was chosen because we expected the extraction to take hours, and unregulated (semi-)volatile DBPs have been shown to be stable around pH 3.7. , We did not conduct SPE at the same pH as XAD resin extraction because high background toxicity can result from leaching from surface-modified styrene divinylbenzene sorbents at pH <2; degradation of other types of SPE sorbents has also been observed at low pH. , Afterward, the solution was loaded onto the SPE cartridge using vacuum at a flow rate of 7 mL/min. After the extraction finished, the SPE cartridge was dried under vacuum for 2 min before eluting with 15 mL of MtBE or EtOAc; this elution targeted the Sepra ZTL sorbent.…”

Section: Materials and Methodsmentioning

confidence: 99%

Disinfection Byproduct Recovery during Extraction and Concentration in Preparation for Chemical Analyses or Toxicity Assays

Lau

Forster

Richardson

et al. 2021

Self Cite

Over 700 disinfection byproducts (DBPs) have been identified, but they account for only ∼30% of total organic halogen (TOX). Extracting disinfected water is necessary to assess the overall toxicity of both known and unknown DBPs. Commonly used DBP extraction methods include liquid–liquid extraction (LLE) and solid-phase extraction (SPE), which may use either XAD resins or other polymeric sorbents. With few exceptions, DBP recoveries have not been quantified. We compared recoveries by LLE, XAD resins, and a mixture of Phenomenex Sepra SPE sorbents (hereafter SPE) for (semi-)volatile DBPs and nonvolatile model compounds at the 1-L scale. We scaled up the three methods to extract DBPs in 10 L of chlorinated creek waters. For (semi-)volatile DBPs, XAD resulted in lower recoveries than LLE and SPE at both 1- and 10-L scales. At the 10-L scale, recovery of certain trihalomethanes and trihalogenated haloacetic acids by XAD was negligible, while recovery of other (semi-)volatile DBPs extracted by XAD (<30%) was lower than by SPE or LLE (30–60%). TOX recovery at the 10-L scale was generally similar by the three extraction methods. The low TOX recovery (<30%) indicates that the toxicity assessed by bioassays predominantly reflects the contribution of the nonvolatile, hydrophobic fraction of DBPs.