聚邻苯二胺—镍电极的电化学研究

本文在ＨＣｌＯ４介质中,用循环伏安法电化学制备了聚邻苯二胺修饰膜电极,探讨了该聚合膜与Ｎｉ＾２＋的配合及其影响因素,关对配合后的膜电极进行了电化学研究。     

聚邻苯二胺膜电极上氧还原为过氧化氢

聚邻苯二胺膜电极上氧还原为过氧化氢陆兆锷，锺天耕，张关永（华东理工大学化学系，上海２００２３７）参考了ＯｈｓａｋａＴ等￣［１－４］的工作，制成聚邻苯二胺（ＰＰＤ）膜覆盖的石墨电极。研究了电极在酸性溶液中对氧还原的电催化作用，氧还原为过氧化氢的电流效率...     

聚邻苯二胺修饰玻碳电极的制备及电催化性能

在磷酸盐缓冲溶液中研究了邻苯二胺在玻碳电极表面的聚合过程,探讨了各氧化还原峰的变化机理,用扫描电镜表征了聚邻苯二胺膜的形态结构。发现制备的聚邻苯二胺膜修饰电极对H2O2有显著的电催化还原特性,线性回归方程为:Δipa(μA)=-1.63 1.07cH2O2(mmol.L-1)(R=0.9947,n=19),线性范围为:5.89×10-2mmol.L-1~44.4 mmol.L-1,检出限为:0.02 mmol.L-1(3S/k),这对与产生H2O2的氧化酶相结合制备出响应各种底物的电化学生物传感器非常重要。考察了制备条件对膜电极电催化还原活性的影响,发现只有在弱酸条件下制备的膜电极才有较高的电催化活性。探讨了影响膜电极电催化还原灵敏度的因素,并考察了膜电极的稳定性。     

聚邻苯二胺膜电极的性能及其对苯醌还原动力学的影响

利用循环伏安法和原位红外反射光谱法研究了pH=7.0的磷酸盐缓冲溶液中聚邻苯二胺(PPD)膜电极的电化学行为。在比0.0V(SCE)负的电位区,PPD呈现氧化还原活性,氧化还原过程伴有H₂PO₄^-离子的嵌入和脱出,证明聚合物带有正电荷。苯醌在该膜电极上的还原反应发生在PPI)的电化学活性电位区内。旋转圆盘电极实验表明,苯配可渗入膜内并与聚合物交换电子。根据PPD为导电聚合物的模型分析了膜电极上苯配还原的动力学并讨论了对其影响的因素。     

聚邻苯二胺膜电极中辣根过氧化物酶的电子传递

利用酸的电化学固定法制备含辣根过氧化物酶的聚邻苯二胺膜电极，研究其伏安行为及对Ｈ２Ｏ２还原的生物电催化作用，结果表明，在所述生物电催化反应中酶与聚合物基质 直接电子传递，但对新制的酶电极而言，电聚合时生成并包埋在酶膜中的寡聚体可作为电子传递体加速氧化态酶的再生，根据酶电极电流响应实验曲线的拟合，发现经态酶的再生速度随是极电位的变化表观上符合Ｔａｆｅｌ关系式，提出了酶反应学参数的测定方法。     

以聚邻苯二胺修饰的镀铂玻碳电极为基底的葡萄糖传感器

生物电化学传感器所面临的主要问题,就是干扰和污染。具有选择渗透性的聚合物膜可以防止电活性物质到达电极表面和大分子物质对基底电极的污染,提高电极的选择性,延长使用寿命。这方面的报道已很多。电聚合的邻苯二胺膜的选择渗透性已有报道。其优点是薄(<10nm),且具有自身的绝缘性,可以被均匀地聚合在电极表面。我们用这种聚合物膜修饰电极为基底电极,化学交联法将葡萄糖氧化酶(GOD)固定在基底电极表面,制备了葡萄糖     

基于聚邻苯二胺@单壁碳纳米管修饰电极用于全血pH测定

开发了一种新型的电流型pH传感器。聚邻苯二胺(PoPD)通过原位电化学聚合法沉积在单壁碳纳米管(SWCNT)修饰的玻碳电极(GCE)表面。利用扫描电子显微镜(SEM)和傅里叶变换红外光谱(FTIR)对所得电极GCE/SWCNT/PoPD进行表征。通过循环伏安法(CV)优化扫描聚合电位和扫描圈数,在最佳实验条件下,研究该传感器对pH的电化学响应。结果表明,该传感器对pH在4.5～8.2具有良好的比率型电流响应。该传感器已成功用于人全血样品pH的直接测定。     

聚萘酚类pH修饰电极的研究

聚合物薄膜修饰电极作为pH传感器研究颇多,这些传感器多为苯胺及其衍生物聚合膜电极,而对在有机合成及生物化学中起着重要作用的萘胺及其衍生物的研究较少。本文以铂丝电极为基体,用电化学方法在其上修饰     

聚邻苯二胺修饰电极应用于硝基苯的测定

研制了聚邻苯二胺薄膜修饰石墨电极,发现其对硝基苯的电化学还原具有明显的催化作用。据此建立了循环伏安法测定硝基苯的新方法。在pH 10.00的磷酸盐缓冲溶液中,硝基苯在-0.83 V处产生一个灵敏的还原峰,在2.00×10-7～1.00×10-5mol/L范围内,硝基苯的还原峰电流与浓度呈良好的线性关系,线性回归方程为ipc(μA)=1.19×107c(mol/L)+9.79(相关系数r=0.997),检出限为5.00×10-8mol/L。将该方法应用于模拟工业废水中硝基苯的测定,加标回收率为94.0%～99.0%。     

Development of pH sensor based on aromatic polyurethane matrix

The synthesized aromatic polyurethane (APU)-based all-solid-state (ASS) pH sensor was developed with the same APU-based reference site in an ASS multi sensing electrode. The best analytical performance (the linear range of pH 3.0–11.5, slopes of 57 mV pH⁻¹) was obtained with the membrane composition of 33:66:1 (wt.%) of APU/plasticizer (NPOE)/ionophore (N,N-dioctadecylmethylamine) with the addition of lipophilic additive (KTpClPB, 5 mol.%). This ASSE exhibits more advantages of increasing stability, reducing membrane resistance and reducing anion interference.     

共价键合修饰壳聚糖pH传感器的研制

以共价键合的方法将壳聚糖修饰到玻碳电极上制成了pH传感器,探讨了该传感器的性能及作用机理.结果表明该传感器在pH 0.7～11.0的范围内电极电势与pH符合Nernst响应,斜率为58.3 mV/pH,可准确测定较高酸度溶液的pH,克服了玻璃pH传感器的"酸误差"的缺点.该传感器内阻小,易微型化,在一定的pH范围内对温度不敏感且具有较好的准确度和重现性,较快的响应速度.可用于雨水和饮料等实际样品溶液的pH的测定.     

CCD camera full range pH sensor array

Changes in colors of an array of optical sensors that responds in full pH range were recorded using a CCD camera. The data of the camera were transferred to the computer through a capture card. Simple software was written to read the specific color of each sensor. In order to associate sensor array responses with pH values, a number of different mathematics and chemometrics methods were investigated and compared. The results show that the use of “Microsoft Excel's Solver” provides results which are in very good agreement with those obtained with chemometric methods such as artificial neural network (ANN) and partial least square (PLS) methods.     

Phenolphthalein immobilized membrane for an optical pH sensor

A phenolphthalein immobilized cellulose membrane for an optical pH sensor was described. The phenolphthalein was first reacted with the formaldehyde to produce a series of prepolymers with many hydroxymethyl groups. In this paper, the prepolymers was abbreviated to phenolphthalein-formaldehyde (PPF). Then the PPF was covalently immobilized to the diacetylcellulose membrane via hydroxymethyl groups. Finally the membrane was hydrolyzed in the 0.1 M NaOH solution for 24 h to reduce the response time. Advantageous features of the pH-sensitive membrane include (a) a large dynamic range from pH 8.0 to 12.50, or even broader, (b) rapid response time (2–30 s), (c) easy of fabrication, and (d) a promising material for determination of high pH values. The immobilized PPF has a broader dynamic range from 8.0 to 12.50 than the free phenolphthalein from pH 8.0 to 11.0, and this was due to the newly produced methylenes in our investigation.     

A hetero-core structured fiber optic pH sensor

Novel spectroscopic sensor based on a hetero-core structured fiber optic is described in this paper. The hetero-core structured fiber optic consists of multi mode fibers and a short piece of single mode fiber which was inserted in the multi mode fibers. Phenol red and/or cresol red as pH sensitive dyes were immobilized on the surface of the hetero-core portion by using sol-gel method, and the pH change detection was performed by immersing the hetero-core portion into the solution. In the case that the cresol-red immobilized fiber was immersed in the alkaline and/or acidic solution, the peak wavelength of the propagating loss spectra were about 575 and 545 nm, respectively. These propagating loss spectra were similar to that of the absorbance spectra of the dye solution. In the propagating loss spectra of phenol-red immobilized fiber, these spectra were similar to that of the dye solution. The colorimetric change of the dye in the support matrix was reversible, and the response time of the sensor was within 30 s.     

石墨烯量子点-金纳米簇比率荧光传感器用于海水pH检测

表层海洋pH正以约每年0.002的速度下降,这种变化将会对地球的化学循环和气候变化的物理化学参数产生潜在的影响。为了准确了解海洋的酸化程度,本文建立了一种快速准确检测海水pH的方法。采用柠檬酸热解法合成石墨烯量子点（GQDs）,以谷胱甘肽（GSH）为模板合成金纳米簇（GSH-AuNCs）,将GQDs和GSH-AuNCs结合制成GQDs-AuNCs比率荧光传感器,用于海水pH的检测。在酸性条件下,由于GSH-AuNCs表面的羧基发生质子化,GSH-AuNCs分子之间的静电斥力减弱因而发生聚集,荧光强度随之降低。在碱性条件下,GSH-AuNCs表面的羧基脱质子化,GSH-AuNCs分子之间的静电斥力增强,荧光强度也随之增强。在pH 2～11范围内,GQDs-AuNCs比率荧光探针的荧光强度比值(I₅₆₅/I₄₄₀)与pH之间呈线性相关。将该方法用于海水的pH检测,得到较好的实验结果。     

Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements

High quality carbonate chemistry measurements are required in order to fully understand the dynamics of the oceanic carbonate system. Seawater pH data with good spatial and temporal coverage are particularly critical to apprehend ocean acidification phenomena and their consequences. There is a growing need for autonomous in situ instruments that measure pH on remote platforms. Our aim is to develop an accurate and precise autonomous in situ pH sensor for long term deployment on remote platforms. The widely used spectrophotometric pH technique is capable of the required high-quality measurements. We report a key step towards the miniaturization of a colorimetric pH sensor with the successful implementation of a simple microfluidic design with low reagent consumption. The system is particularly adapted to shipboard deployment: high quality data was obtained over a period of more than a month during a shipboard deployment in northwest European shelf waters, and less than 30 mL of indicator was consumed. The system featured a short term precision of 0.001 pH (n = 20) and an accuracy within the range of a certified Tris buffer (0.004 pH). The quality of the pH system measurements have been checked using various approaches: measurements of certified Tris buffer, measurement of certified seawater for DIC and TA, comparison of measured pH against calculated pH from pCO₂, DIC and TA during the cruise in northwest European shelf waters. All showed that our measurements were of high quality. The measurements were made close to in situ temperature (+0.2 ?C) in a sampling chamber which had a continuous flow of the ship’s underway seawater supply. The optical set up was robust and relatively small due to the use of an USB mini-spectrometer, a custom made polymeric flow cell and an LED light source. The use of a three wavelength LED with detection that integrated power across the whole of each LED output spectrum indicated that low wavelength resolution detectors can be used instead of the current USB mini spectrophotometer. Artefacts due to the polychromatic light source and inhomogeneity in the absorption cell are shown to have a negligible impact on the data quality. The next step in the miniaturization of the sensor will be the incorporation of a photodiode as detector to replace the spectrophotometer.     

Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements

The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO₂ and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements.     

A pH optical and fluorescent sensor based on rhodamine modified on activated cellulose paper

A rhodamine‐based colorimetric and fluorescent pH chemosensor ( RhA ) was designed and synthesized via a coupling reaction between rhodamine ethylenediamine and succinic anhydride. RhA showed excellent pH response in aqueous solutions. In addition, common cations (Na⁺, K⁺, Ag⁺, Mg²⁺, Ca²⁺, Pb²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Cr³⁺, Fe³⁺, Au³⁺, Pt²⁺, and Ru²⁺) did not interfere with the pH response. As it has the potential to be used as a portable pH sensor, RhA was immobilized on activated cellulose paper using N,N'‐dicyclohexylcarbodiimide (DCC) and N,N'‐dimethylpyridin‐4‐amine (DMAP) as the coupling reagent to obtain a composite pH sensor ( CP‐RhA ). CP‐RhA was characterized by ATR‐FTIR, UV–vis, and fluorescence spectroscopy, and by scanning electron microscopy (SEM). CP‐RhA showed a rapid response in the pH range 1–8 through color and fluorescence changes. DFT calculations showed a blue‐shifted spectrum in the protonated form compared to the neutral form. Moreover, the pH sensor paper could be reused by dipping in NaOH. Thus, our work demonstrates the potential of the rhodamine dye composite for visualizing pH changes in real systems.     

Full-range optical pH sensor array based on neural networks

A neural network multivariate calibration is used to predict the pH of a solution in the full-range (0–14) from hue (H) values coming from imaging an optical pH sensor array based on 11 sensing elements with immobilized pH indicators. Different colorimetric acid-base indicators were tested for membrane preparation fulfilling the following conditions: 1) no leaching; 2) change in tonal coordinate by reaction and 3) covering the full pH range with overlapping between their pH responses. The sensor array was imaged after equilibration with a solution using a scanner working in transmission mode. Using software developed by us, the H coordinate of the colour space HSV was calculated from the RGB coordinates of each element.The neural network was trained with the calibration data set using the Levenberg–Marquardt training method. The network structure has 11 input neurons (each one matching the hue of a single element in the sensor array), 1 output (the pH approximation value) and 1 hidden layer with 10 hidden neurons. The network provides an MSE = 0.0098 in the training data, MSE = 0.0183 in the validation data and MSE = 0.0426 in the test data coming from a set of real water samples. The resulting correlation coefficient R obtained in the Pearson correlation test is R = 0.999.