Globally, tea is the second most consumed non-alcoholic beverage and is an important pathway of disinfection by-product (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 and total organic halogen 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); new DBPs were also identified using GC-high resolution-MS with a nontarget approach. In many cases, measured DBP levels in tea were lower than in the tap water itself due to volatilization and sorption to 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 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 GC-high resolution-MS indicates this may be the case. Current non-target high resolution-MS/MS work is also underway to identify more polar, high molecular weight DBPs using a UHPLC-QTOF mass spectrometer.  Those results will also be presented.  Further studies on the identity and formation of these aromatic DBPs should be conducted, since haloaromatic DBPs can have significant toxicity.

Are DBPs formed in my cup of tea? Regulated, priority, and unknown DBPs

ACS Spring 2022

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