一种用于水中次氯酸根检测的高选择性裸眼比色探针

实时检测和监测水中的次氯酸根离子（ClO-）是极富挑战性的研究工作。报道了一种光学性能优异、“裸眼”可分辨的比色型探针分子（PAH）。首先利用高分辨质谱，核磁共振氢谱和核磁共振碳谱等方法对目标探针分子（PAH）的结构进行表征。随后，利用紫外-可见吸收光谱考察了不同pH缓冲溶液条件下探针PAH与次氯酸根离子的相互作用。结果显示，水溶性的探针分子PAH在pH值为2.0~5.0的磷酸盐缓冲液中为黄色溶液，其最大吸收峰在424 nm处；在pH值为6.0~12.0的磷酸盐缓冲液中PAH为紫色溶液，最大吸收峰在532 nm处；在不同pH缓冲液体系中分别加入次氯酸根离子，肉眼可观察PAH溶液颜色褪去，紫外-可见吸收光谱显示在424 nm处的特征吸收峰逐渐降低并在532 nm处出现新的吸收峰，溶液颜色从黄色到紫色然后到无色，特征峰明显消失。进一步优化了实验条件，发现在pH 5.0的磷酸盐缓冲液中，探针分子PAH对ClO-离子具有特定的选择性和灵敏度，并且具有较低检出限等优点；在优化的条件下，探究了常见的金属离子、阴离子等共存条件下，对探针分子PAH检测次氯酸根离子的干扰影响。实验发现，常见的金属离子（Li+，Co2+，Cr3+，K+，Cd2+，Pb2+，Ca2+，Hg2+，Ba2+，Cu2+，Mg2+，Ni2+，Zn2+，Al3+和Fe3+），阴离子（NO-₂，I-，AcO-，ClO-₄，SO2-₄，CN-，Br-，CO2-₃和F-），活性氧（ROO·，·OH，H₂O₂，·O-₂，tBuOOH，tBuO·和1O₂），和活性氮（ONOO-和NO·）等33种物质对探针分子检测ClO-离子的干扰较小。同时，探针PAH可以定量检测次氯酸根离子（y=1.586 78-0.524 51x，R2=0.998 52），检出限为5.39 μmol·L-1。此外，对水体系（84消毒剂和自来水）中的次氯酸根离子浓度进行分析，三次平行试验测得自来水中次氯酸根离子的平均浓度为7.96 μmol·L-1，平均加标回收率高，表明探针PAH还可用于定量检测实际水体系中的次氯酸根离子。

A Highly Selective Colorimetric Naked-Eye Probe for Hypochlorite Detection in Water

The real-time detection and monitoring of hypochlorites(ClO-)in water is highly challenging.An excellent colorimetric“naked-eye”probe photoacid(PAH)was synthesized.PAH was comfirmed using High-Resolution Mass Spectrometry(HRMS),¹H NMR and ¹³C NMR.The interaction between PAH and ClO-was investigated via UV-Vis absorption spectrophotometry under different pH conditions.The results indicated that PAH was completely soluble in water,PAH displayed a yellow solution in a phosphate buffer with a pH of 2.0 to 5.0,and the maximum absorption peak was at 424 nm.PAH displayed a purple solution in a phosphate buffer with a pH of 6.0~12.0,and the maximum absorption peak was at 532 nm.After adding ClO-to different pH systems,PAH discoloration and the UV-Vis absorption peak disappeared.The probe PAH exhibited specific selectivity and sensitivity for ClO-detection with a low detection limit in the pH 5.0 phosphate buffer.After PAH reacted with ClO-,the absorption peak of the probe at 424 nm gradually decreased,and a new absorption peak appeared at 532 nm.The probe displayed a vivid color-tunable process from yellow to purple then to colorless with a fast response time for ClO-detection.However,other common 33 substances such as metal ions(Li⁺,Co 2⁺,Cr 3⁺,K⁺,Cd 2⁺,Pb 2⁺,Ca 2⁺,Hg 2⁺,Ba 2⁺,Cu 2⁺,Mg 2⁺,Ni 2⁺,Zn^(2⁺),Al 3⁺and Fe 3⁺),anions(NO-2,I-,AcO-,ClO-4,SO₂-4,CN-,Br-,CO₂-3 and F-),reactive oxygen species(ROO·,·OH,H₂O₂,·O-2,t BuOOH,t BuO·and 1O₂)and reactive nitrogen species(ONOO-and NO·),did not cause changes in the color of the probe solution and the UV-Vis absorption spectrum.The above species had only a limited effect on detecting the ClO-anion.When they coexisted with ClO-,the probe also showed a similar solution color change,and the absorption peak at 424 nm disappeared.Meanwhile,the probe PAH could quantitatively detect the content of ClO-with a detection limit of 5.39μmol·L^-1(y=1.58678-0.52451x,R²=0.99852).Furthermore,ClO-concentration in the water system(84 disinfectant and tap water)was analyzed.The average concentration of ClO-ion in the tap water measured by three parallel tests was 7.96μmol·L^-1 with high recoveries rate.It showed that PAH could also be utilized to detect ClO-quantitatively in real water systems.