流动注射化学发光法测定痕量的2,4-二氯酚

随着化学工业的发展迅速,人工合成的有机物种类增多,人类物质文明的同时也带来了严重的环境污染问题.美国环保局于1997年公布的重点控制的污染物129种,2,4-二氯酚便是其中之一.2,4-二氯酚作为一种重要的有机中间体,主要应用于农药工业、医药工业及合成材料等行业.它属于一类环境激素,能通过食物链在动物体内积累.环境中分布或残留的化学物质对人类和野生动物的内分泌系统的不良影响已引起广泛关注.目前分析2,4-二氯酚的方法主要是高效液相色谱法、气相色谱法及气-质联用法等[1,2].     

2,4-二氯苯酚的电化学氧化降解反应研究

采用循环伏安法和原位红外光谱技术研究了2,4-二氯苯酚在Pt电极上的电化学氧化降解反应,结合Fukui函数值预测了2,4-二氯苯酚在电化学氧化过程中的反应位点. 结果表明,Pt电极对2,4-二氯苯酚有良好的电催化活性,2,4-二氯苯酚在电极表面反应主要有3个途径：直接通过电化学反应脱去氯离子,生成苯酚;在·OH的进攻下,C—Cl键断裂,4位Cl较2位Cl先脱去,生成苯二酚,并可进一步氧化生成苯醌以及不饱和羧酸;在·OH的进攻下发生苯环开环反应,生成含氯不饱和羧酸. 在1700 mV左右,2,4-二氯苯酚可经电化学氧化生成CO₂.     

玻璃负载TiO2膜光催化降解2,4-二氯苯酚

玻璃负载TiO2膜光催化降解2;4-二氯苯酚     

2,4-二氯苯氧基乙酸的光转化化学发光机理研究

实验发现,2,4-二氯苯氧基乙酸(2,4-D)经紫外光转化后与KMnO4在H2SO4介质中反应可产生化学发光。采用液相色谱-质谱联用技术(LC-MS)对2,4-D光降解产物进行分析,推断光降解主要生成了多酚类降解产物,如2-氯对苯二酚(CHQ)和4-氯邻苯二酚等。化学发光光谱研究发现,2,4-D经紫外光转化后,与KMnO4反应的发光波长为690 nm,与2,4-D的典型降解产物CHQ的化学发光光谱一致。此发光现象是氧化还原过程中生成的Mn?吸收反应所释放出的化学能成为激发态,再返回基态时产生的特征辐射峰。该反应体系可用于2,4-D的检测,当2,4-D浓度在0.01～10 mg/L范围内与发光强度呈良好的线性关系;检出限为3.0μg/L。     

环境激素类物质2,4-二氯苯酚荧光免疫分析方法的建立

以2,4-二氯苯酚(DCP)与牛血清白蛋白的偶联物DCP-BSA为人工抗原,免疫新西兰大白兔,获得特异性的抗体.建立并优化了荧光免疫检测方法,工作曲线表明DCP在1～100 μg/L范围内呈良好的线性关系,回归方程为:IF=21.30lg ρ 29.13,相关系数r=0.991 5,DCP检出限为0.41 μg/L,抑制中质量浓度为9.18 μg/L,且对其它结构类似酚类化合物均有特异性识别.本法可应用于检测环境中微量的2,4-二氯苯酚.     

紫外分光光度法测定2,4-二氯苯酚

2,4-二氯苯酚被世界野生动物基金会列为潜在的内分泌修正化学物质,即环境荷尔蒙物质.这类物质在环境中虽然含量低,但却显示出超常的内分泌效应,因而对其的监测分析显得尤为重要.目前,分析2,4-二氯苯酚的方法有比色法[1]和色谱法[2].色谱法虽然快速、准确,但对仪器要求高,操作复杂,而比色法灵敏度低.用紫外分光光度法测定河水中的2,4-二氯苯酚.     

纳米级Pd/Fe双金属体系对水中2,4-二氯苯酚脱氯的催化作用

 利用化学沉淀法制备了纳米级Fe和纳米级Pd/Fe双金属催化剂,研究了它们对2,4-二氯苯酚(2,4-DCP)还原脱氯的催化性能. 结果表明,纳米级颗粒具有较高的比表面积和表面反应活性,其BET比表面积可达12.4 m2/g,当Pd/Fe用量为6 g/L时,2,4-DCP脱氯率达到90%以上. 脱氯效率与pH值、温度、钯含量和Pd/Fe投加量等因素有关. 2,4-DCP在脱氯过程中先生成2-氯苯酚和4-氯苯酚,最终生成苯酚,而少量的2,4-DCP可直接降解成苯酚.     

环境荷尔蒙物质2,4-二氯苯酚全抗原的合成与表征

2,4-二氯苯酚是一种对人类健康和生态环境极其有害的环境荷尔蒙物质,因此,对于它的监测分析,具有十分重要的意义.免疫分析已成功用于多种农药及其代谢物的残留分析,显示了其在环境残留分析上的巨大潜力[1,2].目前,国内外尚无2,4-二氯苯酚半抗原设计与抗体制备的相关研究.为此,本研究合成了2,4-二氯苯酚全抗原,为进一步建立免疫分析法检测环境中2,4-二氯苯酚的残留量,提供了可靠的免疫原.本方法的建立对于环境监测、防止污染、保护人体健康具有重要意义.     

催化氢化法制备2,4-二氯-5-异丙氧基苯胺

在乙醇溶液中,控制体系中2,4 二氯 5 硝基苯酚、溴化钠、和水的质量分数分别小于0.3%、0.3%和4%的情况下,用雷尼镍作催化剂,13～15大气压下用氢气还原2,4 二氯 5 异丙氧基硝基苯,得到2,4 二氯 5 异丙氧基苯胺,收率达97%.每次更新10%催化剂,循环使用,催化剂活性未见明显下降.     

2,4-二氯-5-异丙氧基苯胺的合成

1 前言 2,4-二氯-5-异丙氧基苯胺是重要的染料、医药和农药中间体,特别是合成1,2,4,5- 四取代苯类含氮杂环除草剂如口恶草酮、2-[2,4-二氯-5 -(1-甲基乙氧基)苯基]-4-(2-氟乙基)-1,2,4-三嗪-3,5(2H,4H)-二酮等.该中间体合成未见国内文献报道.专利WO 8600072中报道路线是采用间氨基苯酚经酰化、氯化、水解、醚化制得产品(见方程1).     

Simple and convenient chemiluminescence method for the determination of melatonin

A simple and convenient chemiluminescence (CL) method for the determination of melatonin is reported. It is based on the observation that melatonin can greatly enhance the ultra-weak CL between H₂O₂ and acetonitrile in alkaline solution. Light emission is intense and long-lived, and even with a simple setup, a high sensitivity could be achieved. The log-log linear range was 250 nM-250 μM with a 3σ detection limit of 100 nM. Singlet oxygen is suggested to be produced by the reaction between H₂O₂ and acetonitrile and is responsible for the CL of melatonin. As a preliminary application, this simple method has been successfully applied into the determination of melatonin in health-foods.     

Visible light-sensitized semiconductor photocatalytic degradation of 2,4-dichlorophenol

Sensitized-photocatalytic decomposition of 2,4-dichlorophenol (2,4-DCP) using xan-thene dyes as photosensitizer on TiO2 particles under visible light irradiation was studied. 2,4-DCP can be decomposed efficiently by this method and the decomposition efficiency of 2,4-DCP decreases in the following order: eosin Y ≈ rose bengal > erythrosine B > rhodamine B.     

Flow injection chemiluminescence determination of nitrofurazone in pharmaceutical preparations and biological fluids based on oxidation by singlet oxygen generated in N-bromosuccinimide-hydrogen peroxide reaction

A simple flow injection chemiluminescence (FI-CL) method was proposed for the determination of nitrofurazone. Strong CL signal was generated during the reaction of nitrofurazone with H₂O₂ and N-bromosuccinimide (NBS) in alkaline condition. The CL signal was proportional to the nitrofurazone concentration in the range 1.0 × 10⁻⁷ to 1.0 × 10⁻⁵ g mL⁻¹. The detection limit was 2 × 10⁻⁸ g mL⁻¹ nitrofurazone and the relative standard deviation was less than 4% (6.0 × 10⁻⁶ g mL⁻¹ nitrofurazone, n = 11). The proposed method was successfully applied to the determination of nitrofurazone in compound furacillin nasal drops, human plasma and urine samples. The CL reaction mechanism was also discussed briefly. Singlet oxygen generated in the reaction between H₂O₂ and NBS was suggested to be participated in the CL reaction.     

The chemiluminescence mechanism of 3,4-bis(3-indolyl)-1H-pyrrole-2,5-dione, and the characteristics of chemiluminescence developed in the reaction with CH(3)CNH(2)O(2)NaOH

The chemiluminescence (CL) mechanism of 3,4-bis(3-indolyl)-1H-pyrrole-2,5-dione (IPD) was investigated using liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) of the products formed after the IPD CL reaction. We found that IPD produced strong CL via the decomposition of dioxetane formed after oxidation of the maleimide and indole moieties in the presence of CH₃CN, H₂O₂ and NaOH. The IPD CL was used for evaluating the antioxidant effect on curcumin and epigallocatechin gallate.     

Impact of photosensitized oxidation and singlet oxygen on degradation of stabilized polymers

Photooxidation, an important component of polymer weathering, involves excited polymer-inherent chromophores and photoactive additives and impurities. Quenching of excited species by ground state molecular oxygen, the common component of air, results in the formation of singlet state molecular oxygen ¹O₂. This active form of oxygen is a strong oxygenation agent attacking stabilized polymers. Resulting transformations of the polymer matrix and additives have a negative effect on the service life of the material. The formation of ¹O₂, its properties, and reactions and products arising from stabilizers are outlined.     

Chemiluminescence from singlet oxygen that was detected at two wavelengths and effects of biomolecules on it

We developed the detection apparatus that equipped with the two-photomultiplier tubes for chemiluminescence from singlet oxygen. Singlet oxygen was generated with reaction between sodium hypochlorite and hydrogen peroxide. The chemiluminescence from singlet oxygen, the dimol light emission (ca. 634 nm) and the monomol light emission (ca. 1270 nm), was observed simultaneously for the same reaction cell. The effects of sodium azide as an antioxidant, human serum albumin, and α-amino acids on the chemiluminescence based on the both emissions were examined; the observed chemiluminescence could provide direct information with regard to the reaction between singlet oxygen and antioxidant/biomolecules. The apparent rate constants for quenching singlet oxygen in the presence of human serum albumin were calculated to be ca. 3.3 × 10⁹ and ca. 8.8 × 10⁸ M⁻¹ s⁻¹ for the dimol and monomol light emissions, respectively, under the present conditions. The chemiluminescence intensities of the dimol emission decreased in the presence of His, Asp, Phe, Ser, and Tyr, and that of the monomol decreased in the presence of Cys and Trp. The chemiluminescence observed in the presence of biomolcules was discussed together with the reactivities of sodium hypochlorite and hydrogen peroxide to biomolecules.     

A new chemiluminescence probe for singlet oxygen based on tetrathiafulvalene-anthracene dyad capable of performing detection in water/alcohol solution

A new tetrathiafulvalene-anthracene dyad 1 with two “tetraethylene glycol” units was synthesized and characterized. Strong chemiluminescence was observed upon reaction of dyad 1 with singlet oxygen (¹O₂), and this reaction shows fairly good selectivity toward ¹O₂ over other reactive oxygen species. Due to the introduction of two hydrophilic “tetraethylene glycol” units, the detection of ¹O₂ with dyad 1 can be performed in alcohol/water solution, which is relatively a mild medium when compared with water/tetrahydrofuran solution required by other tetrathiafulvalene-anthracene dyads. Dyad 1 may have a wider use for detection of ¹O₂ in biological systems.     

Online phototransformation–flow injection chemiluminescence determination of triclosan

A highly selective and sensitive chemiluminescence method for the determination of triclosan is proposed. The method is based on the phototransformation of triclosan to a light-emitting precursor in the presence of fluorescein in alkaline medium and the chemiluminescence reaction is then triggered by strong base or oxidants such as N-bromosuccinimide. Based on this reaction an online phototransformation–flow injection manifold was developed, in which the photoreactor comprises a 150-cm-long × 0.8-mm-i.d. piece of PTFE tubing coiled around a 25-W fluorescent lamp, and the phototransformed products were then injected into a carrier stream of borate buffer. After mixing with the oxidant stream the produced light was detected by a photomultiplier. A wide calibration range from 8.0 × 10⁻⁸ to 1.0 × 10⁻⁴ mol L⁻¹ was obtained under the optimized conditions, and the detection limit was as low as 5.0 × 10⁻⁸ mol L⁻¹. The whole process of analysis, including the online phototransformation and subsequent chemiluminescence detection, could be completed in 6 min. Most of the foreign substances tested showed high tolerance levels, and the proposed method was directly applied to the determination of triclosan in toothpaste samples without any pre-separation procedure. Figure Schematic representation of the phototransformation of triclosan and subsequent chemiluminescence reaction     

IrSnOx电极制备及其在电氧化制备2,5-二氯苯酚中的应用

采用热分解法制备钛基IrSnO_x电极,并将电极应用于电催化氧化对二氯苯制备2,5-二氯苯酚,探索了绿色高效的电合成途径. 结果表明,电极表面存在裂纹,中间层Sn:Sb为94:6时裂纹较少,强化寿命较长;电极对对二氯苯电氧化具有较好的循环伏安响应;IrSnO_x电极电催化氧化对二氯苯所得产物主要为2,5-二氯苯酚、1,2,4-三氯苯、对氯苯酚等,其中2,5-二氯苯酚选择性达93%,产率57%,显著优于以析氯电极、析氧电极、铂为阳极时,2,5-二氯苯酚的选择性89%、27%、87%和30%、15%、49%的产率,体现了优良的电催化氧化性能.