基于钯纳米线阵列修饰电极的抗坏血酸电化学研究

以氧化铝模板为基础,采用电化学沉积方法制备了钯纳米线阵列修饰金电极。电化学方法研究了该修饰电极对抗坏血酸电化学行为,实验结果表明,抗坏血酸在高度有序的钯纳米线饰电极表面出现显著的氧化峰。氧化峰的峰电流与抗坏血酸的浓度在4.0×10-4~3.15×10-3 mol/L范围内有良好的线性关系,检测限可达1×10-4 mol/L。该电极制备方便,有良好的灵敏度和稳定性。     

Electrochemical noise analysis on multiple dissimilar electrodes: Theoretical analysis

The electrochemical potential and current noise generated by multiple electrodes are analyzed by considering the current flowing across each electrode and the electrochemical potential of the electrode array. By introducing the concept of a “virtual electrode”, the analysis of the electrochemical noise generated by an array of electrodes is reduced to the case of two dissimilar electrodes. For each electrode, an apparent impedance, Z_ρ*, can be determined as the square root of the power spectral density of potential divided by the power spectral density of the individual electrode current. When two dissimilar pairs of nominally identical electrodes are used and it is possible to assume that the pair of electrodes corroding more produces higher noise levels and displays lower impedance, the actual electrode impedance can be obtained with acceptable precision from the value of the nominal impedance. Further, the asymmetry between the two dissimilar pairs can also be quantitatively evaluated.     

系列尼古丁PVC膜选择性电极的研制

以尼古丁为研究对象 ,研制了一系列含有不同增塑剂 (苯二甲酸二辛酯、苯二甲酸二壬酯和癸二酸二辛酯 )和电活性物质 (尼古丁 四苯硼缔合物、尼古丁 硅钨酸缔合物、尼古丁 磷钨酸缔合物和尼古丁 雷氏盐缔合物 )的PVC膜电极。所有的 8支电极均对尼古丁盐酸溶液有Nernst响应。所制备的电极中 ,以尼古丁 四苯硼缔合物、尼古丁 硅钨酸缔合物、尼古丁 磷钨酸缔合物或尼古丁 雷氏盐缔合物为活性物的电极 ,其线性范围达到 10 - 4～ 10 - 1 mol/L ,以尼古丁 硅钨酸缔合物为活性物的电极线性范围达到 10 - 5～ 10 - 1 mol/L。电极响应的均匀性还在进一步的研究和改善中     

Development of multisensor systems based on chalcogenide thin film chemical sensors for the simultaneous multicomponent analysis of metal ions in complex solutions

A new type of thin film chemical microsensors based on chalcogenide glass-sensitive materials was developed by means of silicon planar technology and pulsed laser deposition technique. These miniaturised ion-selective electrodes (ISEs) exhibit Nernstian responses over five concentration decades with detection limits of 1×10⁻⁷ mol/l towards the primary ions Cu and Pb, and 4×10⁻⁷ and 3×10⁻⁵ mol/l towards Cd and Tl, respectively. The thin film microsensors have been shown to be perspective instruments for the simultaneous multicomponent analysis of complex liquid media based on the principles of an ‘electronic tongue’ device. Incorporating the thin film sensors into a sensor array allowed the multicomponent analysis of heavy metal-ion species (Pb²⁺, Cd²⁺, Zn²⁺ and Fe³⁺). The concentrations of Pb²⁺-, Cd²⁺- and Zn²⁺-ions can be determined simultaneously by direct potentiometric measurements using a sensor array of seven all-solid-state thin film chemical microsensors with an accuracy of 15–30%. The sensor array allows overcoming the problem of an insufficient selectivity of single sensors. The suggested microsystem-compatible fabrication technique favours a further miniaturisation, aimed to a fully integrated electrochemical microsystem.     

聚吡咯-酰基吡唑啉酮复合膜修饰玻碳电极测定酚磺乙胺的研究

报道了一种新型聚吡咯-酰基吡唑啉酮复合膜修饰玻碳电极(Ppy/HPMαFP/GCE)对酚磺乙胺(ETH)电化学性质及其反应机理的研究。酚磺乙胺的电化学性质检测运用循环伏安法和脉冲伏安法。实验表明,与裸GCE和Ppy/GCE相比,Ppy/HPMαFP/GCE修饰电极对酚磺乙胺有良好的催化作用。聚吡咯与酰基吡唑啉酮产生了协同增效作用。在pH=5.5的磷酸盐(PBS)缓冲溶液中,该修饰电极测试ETH的CV曲线于0.35V和0.4V出现一对灵敏的氧化还原峰,峰电位差△Ep较裸玻碳电极降低510mV,比Ppy修饰电极降低100mV,峰电流显著增加。在最佳条件下,氧化峰电流与ETH浓度于2.0×10-6~1.0×10-4mol.L-1范围内呈现良好的线性关系,检出限为6.0×10-7mol.L-1。     

Neurophysiological Effects of Naturally Occurring Defensive Compounds on the Freshwater Snail Planorbis corneus: Comparison with Effects in Insects

The essential oil constituents citral, geraniol, and eugenol have toxic or repellent properties that are utilized by a variety of organisms to deter natural enemies. Their mechanism of action is unknown, but some essential oils such as eugenol are claimed to act on insects by specific binding to octopamine receptors. We studied their effects on the isolated buccal ganglia of Planorbis corneus, having demonstrated that they caused cessation of feeding and death when added to the aquarium water (approximately 5 x 10(-4) mol l(-1)). They abolished spike activity at 2 x 10(-3) mol l(-1) but at lower doses (threshold 5 x 10(-5) mol l(-1)) they resembled octopamine in eliciting burst firing indicative of the fictive feeding sequence. However, the octopamine antagonists phentolamine (10(-5) mol l(-1)), yohimbine (10(-4) mol l(-1); which blocked hyperpolarizing octopamine responses), and metoclopramide (10(-4) mol l(-1); which blocked depolarization) had no effect on any of the responses to the oils. The oils produced incomplete block of excitatory and inhibitory responses to octopamine even at high doses (10(-3) mol l(-1)), and they had similar effects on responses to dopamine and acetylcholine. The oils (10(-5)-2 x 10(-3) mol l(-1)) all increased the frequency of contractions of the isolated esophagus and progressively reduced their amplitude. The effects were similar to those of octopamine but were not blocked by phentolamine, metoclopramide, or prolonged exposure of the esophagus to octopamine. The results suggest a variety of actions that could contribute to toxic effects in molluscs, but there was no evidence for specific actions on octopamine receptors, either as agonists or antagonists. Evidence is presented that nonspecific depolarization produces their octopamine-like actions.     

锡砷冶金物料中硝酸盐的直接电极电位法研究

采用离子选择性电极分析技术,在硫酸铝-硫酸银-硼酸-氨基磺酸离子强度剂体系中对锡酸钠、砷酸液等两种物料中的硝酸盐进行检测。用稀酸碱沉淀分离不大于0.80g锡酸根或25mg铁、锑、钙,200mg砷不产生干扰,硝酸盐浓度在3.23×10-5mol/L～1.61×10-2mol/L内电极响应符合能斯特方程式（斜率≥90%）,检测下限可达1.61×10-5mol/L,相对标准偏差（m=6,n=5～11）为1.44%～9.64%,加标回收率为86.0%～123.4%。     

EDTA-Cu（Ⅱ）配合物与纳米TiO2混合修饰碳糊电极测定镉离子

将EDTA-Cu(Ⅱ)配合物与纳米TiO2混合修饰到碳糊电极上,用循环伏安法考察了修饰电极测量镉离子的实验优化条件和电极稳定性。结果表明:在底液0.10 mol/L pH=4.5的HAc-NaAc缓冲溶液(含0.10 mol/L的KNO3)中,当镉离子在修饰电极表面富集10 min,电位扫描速度控制在100 mV/s时,峰电流与Cd2+浓度在1.0×10-8～1.0×10-5mol/L的范围内成良好的线性关系,相关系数为R=0.9965,检出限为6.1×10-9mol/L。     

NiO-based composite electrode with RuO2 for electrochemical capacitors

NiO/RuO₂ composite materials were prepared for use in electrochemical capacitors (ECs) by co-precipitation method followed by heat treatment. X-ray diffraction (XRD) spectra indicated that no new structural materials were formed and ruthenium oxide particles were coated by NiO particles. RuO₂ partly introduced into NiO-based electrode had improved its electrochemical performance and capacitive properties by using electrochemical measurements. A maximum specific capacitance of 210 F/g was obtained for NiO-based composite electrode with 10 wt.% RuO₂ in the voltage range from −0.4 to 0.5 V in 1 mol/l KOH solution. By comparison of effect of modified modes on the specific capacitance, chemically modified composite electrodes had more stable cycling properties than those of physically modified electrodes. After 200 cycles, specific capacitance of NiO-based chemical composite electrode with 5 wt.% RuO₂ kept 95% above, while that of physical electrode was only 79% of initial specific capacitance.     

2-十七烯基-N-氨乙基咪唑啉的极谱法定量测定研究

基于咪唑啉衍生物2-十七烯基-N-氨乙基咪唑啉在氨水NH4Cl介质中产生的阴极波,拟定了该化合物的定量测试方法。在0.004mol/LNH4Cl和0.196mol/L氨水(三次去离子)底液中,该阴极波二阶导数峰电流与2十七烯基N氨乙基咪唑啉浓度在5.0×10-5～1.0×10-4mol/L范围内呈线性关系,线性回归系数0.9996。平均回收率为99.7%,相对标准偏差为3%。可以用于日常生产的质量控制。     

A strategy for selective detection based on interferent depleting and redox cycling using the plane-recessed microdisk array electrodes

The fabrication, characterization and application of the plane-recessed microdisk array electrodes for selective detection are demonstrated. The electrodes, fabricated by lithographic microfabrication technology, are composed of a planar film electrode and a 32 × 32 recessed microdisk array electrode. Different from commonly used redox cycling operating mode for array configurations such as interdigitated array electrodes, a novel strategy based on a combination of interferent depleting and redox cycling is proposed for the electrodes with an appropriate configuration. The planar film electrode (the plane electrode) is used to deplete the interferent in the diffusion layer. The recessed microdisk array electrode (the microdisk array), locating within the diffusion layer of the plane electrode, works for detecting the target analyte in the interferent-depleted diffusion layer. In addition, the microdisk array overcomes the disadvantage of low current signal for a single microelectrode. Moreover, the current signal of the target analyte that undergoes reversible electron transfer can be enhanced due to the redox cycling between the plane electrode and the microdisk array. Based on the above working principle, the plane-recessed microdisk array electrodes break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction, which is a limitation of single redox cycling operating mode. The advantages of the plane-recessed microdisk array electrodes are verified by detecting dopamine in the presence of ascorbic acid and detecting pyrocatechol in the presence of hydroquinone, i.e., the electrodes can work regardless of the reversibility of interfering species.     

Layer-by-layer assembly of single-walled carbon nanotube-poly(viologen) derivative multilayers and their electrochemical properties

Layer-by-layer (LBL) multilayers of oxidized single-walled carbon nanotubes (SWCNTs) and poly(octylviologen) derivative (POV) have been assembled on gold electrode surfaces. The assembling process was characterized by quartz crystal microbalance (QCM) and electrochemical measurements. The average mass change was about 0.726 and 0.381 μg for each assembly of SWCNTs and POV, respectively. Cyclic voltammograms of the LBL multilayer modified electrodes showed well-reversible redox waves centered at about −640 mV vs Ag/AgCl, corresponding to the normal redox reaction of viologens. These LBL multilayers were very stable in the air and 1 mol/l KCl electrolyte solution. The results of QCM, cyclic voltammograms and chronocoulomograms of the multilayer modified Au electrodes indicated that the oxidized SWCNTs could not only support the formation of stable multilayers but also act as an electron mediator between viologens and electrodes.     

Electrochemical detection of catechol at integrated carbon nanotubes electrodes

The mechanical stability of the electrode plays a very important role in the long-term stability of electrochemical behavior. In this paper, multi-wall carbon nanotubes (MWCNTs) electrodes were prepared in the holes of glass directly by microwave plasma chemical vapor deposition and the electrochemical behavior of catechol at the integrated MWCNT electrodes was investigated. The oxygen plasma treated CNTs had excellent electrochemical behavior for the analysis of catechol. The catechol was detected in the linear concentration range of 1.0 × 10^− 6 mol L^− 1–1.0 × 10^− 3 mol L^− 1. And because CNTs were integrated directly on the substrate, the stable response to catechol solution showed that the carbon nanotubes electrodes had long-term stability.     

以利福平为载体的静松灵兽药电极的研制

研制了以利福平(rifanpicin)为活性载体的静松灵选择性电极。该电极在pH 4.00～9.00的10-2mol/L NaCl的水溶液中,测定静松灵的线形响应范围为1.0×10-2～6.50×10-6mol/L,斜率为57.8 mv/pC,检测下限为5.01×10-7mol/L。电极响应快,重现性和稳定性好。     

马来酸乙二醇酯、丙烯酸共聚物合成与在水质稳定上的应用研究

合成了马来酸与乙二醇的酯化物。用该酯化物与丙烯酸二元共聚，及用该酯化物、丙烯酸、马来酸酐三元共聚，得到了两种共聚物。讨论了二元共聚物的特性粘数与单体用量的关系，并测定了二元共聚物及三元共聚物对Ｃａ２＋的螯合能力。     

Nanotubes and Nano-TiO_2 Mixed Modified Carbon Paste Electrode for Determination of Cu~（2＋）

用碳纳米管和纳米TiO2混合修饰碳糊电极,用循环伏安法考察了修饰电极测量Cu的优化条件及其电化学稳定性。结果表明,在pH=5.5的HAc-NaAc缓冲溶液中,当Cu2＋在修饰电极表面富集200 s、电位扫描速率控制在60 mV/s时,修饰电极在循环伏安图上能出现1个灵敏氧化峰,峰电位为0.141V,利用这个峰可以对Cu进行检测。峰电流与Cu2＋的浓度在1.0×10-7～1.0×10-4 mol/L的范围内成良好线性关系,相关系数为0.994 4,检出限为1.43×10-8mol/L。     

纳米碳管和纳米二氧化硅修饰玻碳电极示差脉冲伏安法测微量铜

本文用纳米碳管和纳米二氧化硅修饰的玻碳电极以1mol/LH2SO4为底液测定Cu^2＋,方法是先在-0．5V进行预还原120s,然后用示差脉冲伏安法进行阳极扫描,发现在-0．04V（vs．SCE）处出现铜的氧化峰,且峰电流与Cu^2＋的浓度在5．0×10^-8～1．0×10^-2mol/L范围内呈良好的线性关系,该方法的检出下限为1．0×10^--8mol/L。用标准加入法测得回收率范围为92．3％～104．2％,相对标准偏差（RSD）为3．5％。将此电极用于实际样品的测定,取得较好的结果。     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

新型荧光试剂5-(4-溴苯偶氮)-8-(8-喹啉重氮氨基)喹啉的合成及其分析应用

将具有荧光特性的8-氨基喹啉结构与具有良好特性的三氮烯结构相结合,首次合成了标题化合物。其结构经过元素分析、红外光谱、核磁共振谱证实。研究表明,在碱性介质中,该试剂在λex/λem=416 nm/512 nm处产生强荧光,并且能被Cu2+荧光增强。基于此,建立了BPAQAQ测定Cu2+的新型荧光分析法。该方法的线性范围为1.4×10-8~1.0×10-5mol/L,检测限为1.1×10-8mol/L。将其应用于大米粉和小麦粉中Cu2+的测定,结果满意。     

Calcium-induced membrane microdomains trigger plant phospholipase D activity

Plant alpha-type phospholipase D proteins are calcium-dependent, lipolytic enzymes. The morphology of the aggregates of their phospholipid substrate fundamentally defines the interaction between the enzyme and the surface. Here we demonstrate that the Ca(2+)-induced generation of membrane microdomains dramatically activates alpha-type phospholipase D from white cabbage. 500-fold stimulation was observed upon incorporation of 10 mol % 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate (POPA) into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles in the presence of Ca(2+) ions. Enhanced association of PLDalpha2 with phospholipid surfaces containing anionic components was indicated by lag phase analysis and film balance measurements. Differential scanning calorimetry showed that the POPA-specific activation correlates with the phase behavior of the POPC/POPA vesicles in the presence of Ca(2+) ions. We conclude from the results that the Ca(2+)-induced formation of POPA microdomains is the crucial parameter that facilitates the binding of PLD to the phospholipid surface and suggest that this effect serves as a cellular switch for controlling PLD activity.