Applications of 1,3,5-trimethoxybenzene as a derivatizing agent for quantifying free chlorine, free bromine, bromamines, and bromide in aqueous systems
Applications of 1,3,5-trimethoxybenzene as a derivatizing agent for quantifying free chlorine, free bromine, bromamines, and bromide in aqueous systems
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DOI：
10.1039/c9ay01443h
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发表时间：
2019-11-21
影响因子：
3.1
通讯作者：
Sivey, John D.
中科院分区：
文献类型：
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作者：
Dias, Ryan P.;Schammel, Marella H.;Sivey, John D.
游离氯和游离溴（例如 HOCl 和 HOBr）在各种水系统中用作消毒剂，包括饮用水、废水、压载水、娱乐用水和清洁产品。然而，最广泛使用的游离卤素定量方法，包括使用 N,N-二乙基对苯二胺 (DPD) 的方法，无法区分 HOCl 和 HOBr。在此，我们报告了使用 1,3,5-三甲氧基苯 (TMB) 选择性定量各种水性体系中游离卤素的方法。在接近中性的 pH 值下，TMB 与 HOCl、HOBr 和无机溴胺在几秒的时间内发生反应，生成卤化产物，这些卤化产物很容易通过液相色谱法或液-液萃取后的气相色谱-质谱法 (GC-MS) 进行定量。 TMB的氯化和溴化产物是稳定的，它们的摩尔浓度分别用于计算HOCl（GC-MS的方法定量限（MQL）= 15 nmol L-1 = 1.1 μ g L-1作为Cl-2）和HOBr（GC-MS的MQL = 30 nmol L-1 = 2 μ g L-1作为Cl-2）的原始浓度。此外，TMB 衍生化可有效定量饮用水、泳池水、氯化地表水和经 1-溴-3-氯-5,5-二甲基乙内酰脲处理的模拟温泉水中的活性卤化剂。 TMB 还用于定量 20 种名义上不含溴化物的试剂中作为痕量杂质的溴化物（在溴化物被 HOCl 氧化为 HOBr 后）。测试了几种可能的干扰物，并确定碘化物会妨碍 HOCl 和 HOBr 的准确定量。总体而言，与 DPD 方法相比，TMB 可以提供更低的 MQL、更大的线性范围以及 HOCl 和 HOBr 之间的选择性。
Free chlorine and free bromine (e.g., HOCl and HOBr) are employed as disinfectants in a variety of aqueous systems, including drinking water, wastewater, ballast water, recreational waters, and cleaning products. Yet, the most widely used methods for quantifying free halogens, including those employing N,N-diethyl-p-phenylenediamine (DPD), cannot distinguish between HOCl and HOBr. Herein, we report methods for selectively quantifying free halogens in a variety of aqueous systems using 1,3,5-trimethoxybenzene (TMB). At near-neutral pH, TMB reacted on the order of seconds with HOCl, HOBr, and inorganic bromamines to yield halogenated products that were readily quantified by liquid chromatography or, following liquid-liquid extraction, gas chromatography-mass spectrometry (GC-MS). The chlorinated and brominated products of TMB were stable, and their molar concentrations were used to calculate the original concentrations of HOCl (method quantitation limit (MQL) by GC-MS = 15 nmol L-1 = 1.1 mu g L-1 as Cl-2) and HOBr (MQL by GC-MS = 30 nmol L-1 = 2 mu g L-1 as Cl-2), respectively. Moreover, TMB derivatization was efficacious for quantifying active halogenating agents in drinking water, pool water, chlorinated surface waters, and simulated spa waters treated with 1-bromo-3-chloro-5,5-dimethylhydantoin. TMB was also used to quantify bromide as a trace impurity in 20 nominally bromide-free reagents (following oxidation of bromide by HOCl to HOBr). Several possible interferents were tested, and iodide was identified as impeding accurate quantitation of HOCl and HOBr. Overall, compared to the DPD method, TMB can provide lower MQLs, larger linear ranges, and selectivity between HOCl and HOBr.