Simultaneous Detection of Copper,Lead and Zinc on Tin Film/Gold Nanoparticles/Gold Microelectrode by Square Wave Stripping Voltammetry

In this work, three heavy metals (Cu(II), Pb(II) and Zn(II)) in wide potential window were simultaneously detected on tin film/gold nanoparticles/gold microelectrode (Sn/GNPs/gold microelectrode) by the method of square wave stripping voltammetry. The Sn/GNPs/gold microelectrode was fabricated by in situ plating of a Sn film on a gold nanoparticles (GNPs) modified gold microelectrode. The influence of hydrogen overflow on stripping of Zn(II) on the gold microelectrode was reduced by modification of GNPs, which made the stripping potential of target metals shift positively. The interference of sulfhydryl groups was reduced and the selectivity of the microelectrode was improved due to the addition of Sn in the detection solution. After accumulation at ?1.4 V for 300 s in acetate buffer solution (0.1 mol L^?1, pH 4.5), the Sn/GNPs/gold microelectrode revealed a good linear behavior in the examined concentration ranges from 5 to 500 µg L^?1 for Cu(II) and Pb(II), and from 10 to 500 µg L^?1 for Zn(II), with a limit of detection of 2 µg L^?1 for Cu(II), 3 µg L^?1 for Pb(II) and 5 µg L^?1 for Zn(II) (S/N=3). When compared with a Sb/GNPs/gold microelectrode and a Bi/GNPs/gold microelectrode, the Sn/GNPs/gold microelectrode showed the best stripping performance to Cu(II), Pb(II) and Zn(II). As a new type of environment‐friendly electrode, the Sn/GNPs/gold microelectrode has potential applications for detection of heavy metals.     

Formation of Ordered Arrays of Gold Nanoparticles from CTAB Reverse Micelles

In this presentation, a reverse micelle technique was described to create colloid gold nanoparticles and their self-organization into superstructures. Gold nanoparticles were prepared by the reduction of HAuCl₄ in CTAB/octane+1-butanol/H₂O reverse micelle system using NaBH₄ as reducing agent. Dodecanethiol (C₁₂H₂₅SH) was used to passivate the gold nanoparticles immediately after formation of the gold colloid. After re-dispersing in toluene under ultrasonication, a supernatant containing nearly monodispersed dodecanethiol-capped gold nanoparticles was obtained. Self-organization of the gold nanoparticles into ID, 2D and 3D superstructures was observed on the carbon-coated copper grid by TEM. A representative TEM mirograph of the 2D array is shown in Fig. 1. UV/Vis absorption spectra were also used to characterize the gold colloids with and without dodecanethiol capping.     

Gold‐Catalyzed Homogeneous Oxidative Cross‐Coupling Reactions

Oxidizing gold? A gold(I)/gold(III) catalytic cycle is essential for the first oxidative cross‐coupling reaction in gold catalysis. By using Selectfluor for gold(I) oxidation, this chemistry reveals the synthetic potential of incorporating gold(I)/gold(III) catalytic cycles into contemporary gold chemistry and promises a new area of gold research by merging powerful gold catalysis and oxidative metal‐catalyzed cross‐coupling reactions.

     

Critical evaluation of spiking of low-grade ore samples in activation analysis for gold and uranium

In applying non-destructive neutron-activation analysis for gold and uranium in spiked low-grade ore samples, the following extrapolated unspiked concentrations were measured: 0.27₈ ± 0.01₅ ppm gold (chemical assay: 0.20₂ ± 0.02₀ ppm gold); 25.1 ± 1.1 ppm uranium (chemical assay value: 19.5 ±2.0 ppm uranium). Different approaches to the fitting of results, and the influence of spiking non-uniformity, are discussed.     

二丁基卡必醇萃淋树脂吸萃金的性能及其机理的研究

研究了二丁基卡必醇（ＤＢＣ）萃淋树脂吸萃金的机理，溶液酸效应、吸附等温线、吸附速炫、盐析剂应柱操作条件等，将该树脂用于矿样中金含是珠测定，结果与７１７离子交换树脂吸附法一致。     

Application of Inductively Coupled Plasma-Atomic Emission Spectrometry/Mass Spectrometry to Phase Analysis of Gold in Gold Ores

Inductively coupled plasma-atomic emission spectrometry/mass spectrometry (ICP-AES/MS) is a potentially powerful tool in chemical phase analysis of gold in batch mode, especially applicable to the low-grade gold ores with gold content of far below detection limit of the other methods, but it has not been used in gold phase analysis of gold ores. In this work, three types of typical gold deposits (altered rock type, quartz vein type, and microscopic disseminated type) and national standard reference materials of gold ores were used to establish and validate a method for gold phase analysis of gold ores using ICP-AES/MS. The optimum conditions of phase analysis were determined, including the sample granularity and preparation procedures, separation absorbent, pretreatment procedures of various phases of gold and optimized instrument parameters. Evaluation of the optimized method showed that this method had acceptable precision (RSD: 1.1%–10.6%) and accuracy (relative error, RE: 0.5%–6.3%), and the detection results of gold in ores were comparable with those obtained using the hydroquinone volumetric method-extraction flame atomic absorption spectrometry (VOL-AAS) and graphite furnace atomic absorption spectrometry (GFAAS) methods. The sum content of gold of the 4 phases (free gold, F_Au; linked gold, L_Au; sulphide-bearing gold, S_Au; and other mineral-bearing gold, A_Au) conformed to the total gold content and was consistent with the results of rock-mineral identification. The proposed method had a low detection limit (0.30 ng g^–1) and wide linear range (5.0 ng mL^–1–20.00 μg mL^–1). It is a simple, rapid, and efficient method for gold phase analysis in batch form.     

快捷两步法制备金纳米电极用于活体多巴胺检测

用微电极进行活体检测神经化学物质属于侵入式分析,会对脑组织产生不可避免的损伤,进而在生理上产生一些信号干扰检测过程. 减小电极的尺寸对于减小对脑组织的损伤非常重要. 该研究报道了一种新型制备金纳米电极的方法并将其用于活体鼠脑内多巴胺分析研究. 这种金纳米电极的制备过程包含两步：1）通过离子溅射在毛细管的尖端覆盖一层金种子;2）把覆盖有金种子的毛细管浸入氯金酸和盐酸羟胺混合溶液中湿法沉积生成连续导电金膜. 制备好的纳米电极尖端约300 ~ 400 nm. 该金纳米电极可以应用于多巴胺的检测,并且在多巴胺浓度1.0 ~ 56.0 μmol·L^-1范围内有很好的线性响应,最低检测限低至0.14 μmol·L^-1（信噪比=3）. 该金纳米电极具有优异的电化学性能,可以成功的应用于检测鼠脑纹状体儿茶酚胺的释放.     

Determination of arsenic in gold by flow injection inductively coupled plasma mass spectrometry with matrix removal by reductive precipitation

Arsenic was determined in gold by flow injection hydride generation inductively coupled plasma-mass spectrometry following a batch mode reductive precipitation removal of the interfering gold matrix. A solution of potassium iodide, L-ascorbic acid, and hydrochloric acid was used as the reluctant. The recovery of gold by precipitation and filtration was 99 ± 3%. The detection limit for arsenic in gold was 55 ng g⁻¹ in the solid. The concentration of arsenic that was determined in the Royal Canadian Mint gold sample FAU-10 was 29.7 μg g⁻¹ in the solid; this value was indistinguishable, with 95% confidence, from values determined at the Royal Canadian Mint by graphite furnace atomic absorption spectrometry and by inductively coupled plasma-mass spectrometry. The standard deviation for four replicate determinations of the arsenic in FAU-10 was 0.972 μg g⁻¹ in the solid.     

单分散球状纳米金颗粒的合成*

综述了近年来单分散球状金纳米颗粒的合成研究进展。分析了球状单分散金纳米颗粒的应用前景,介绍了单分散球状金纳米颗粒的主要合成方法如种子生长、回流熟化、尺寸选择沉淀分级以及电泳法等,评述了各种方法的优缺点。最后提出了单分散球状金纳米颗粒合成的一些问题,并展望了单分散球状金纳米颗粒的研究和发展方向。     

维生素B_1自组装膜修饰金电极对多巴胺、尿酸的电催化作用

用维生素B1(VB1)在金电极上进行自组装,制备了VB1自组装膜修饰金电极(VB1-Au/SAMs/CME).利用循环伏安法初步研究了此自组装单分子膜修饰电极的电化学行为.结果表明: VB1在金电极表面具有特性吸附.以\3-/ 4-氧化还原电对为探针,考察了VB1自组装膜修饰金电极的电化学性质, VB1自组装膜的存在对\3-/4-的电子转移具有明显的阻碍作用.研究了多巴胺(DA)和尿酸(UA)在此电极上的电化学行为.实验结果表明, DA和UA在此电极上均可被电催化氧化.差分脉冲伏安(DPV)氧化峰电流与DA浓度在2.0×10-5～4.0×10-4 mol/L范围内呈线性关系;测定UA的线性范围为6.0×10-5～2.2×10-4 mol/L,而且可实现这两种物质的同时测定.     

小尺寸金纳米棒的快速制备及影响因素的研究

通过研究十六烷基三甲基溴化铵、抗坏血酸、NaBH4和AgNO3的用量,以及搅拌时间、反应时间对无种子生长法制备金纳米棒的影响,筛选出了最佳制备条件,以及各成分对金纳米棒生长过程中的作用.采用可见吸收光谱和透射电镜图对不同条件下所制备出的金纳米棒进行了表征.在室温为28℃,CTAB浓度为0.1 mol/L、AgNO3浓度为96μmol/L、AA浓度为0.97 mmol/L、NaBH4浓度为1.5μmol/L,搅拌25 s等最佳条件下,只需反应6h就能够成功制备出长径比为5且形貌均匀、分散性和稳定性良好、轴宽较小的金纳米棒,且有望应用于水环境中Hg2+的检测.     

Detection of Heavy Metal Ions Using Synthesized Amino Thiol Surfactants Assembled on Gold Nanoparticles

In this work, we synthesized amino thiol surfactants, namely, 10-(4-aminophenoxy)-decane-1-thiol and 12-(4-aminophenoxy)-dodecane-1-thiol. The self-assembling of the synthesized surfactants on gold nanoparticles (AuNPs) was investigated using different techniques such as ultraviolet analysis, x-ray diffraction, and transmission electron microscopy. The synthesized surfactants show the ability to assemble on gold nanoparticles and form stable nanostructure with it. We used the synthesized surfactants and their nanostructures with gold nanoparticles for the detection of Zn and Ni ions in aqueous solution using the ultraviolet spectrophotometer technique. The synthesized amino thiol surfactants showed the ability to detect Zn and Ni ions at low concentration. The results showed that gold nanoparticles can enhance the detection of Zn and Ni ions using the nanostructures of the synthesized surfactants.     

Determination of gold in leach liquors by anodic stripping voltammetry in non-aqueous medium

The anodic stripping voltammetry of gold in butyl acetate/methanol (2 + 1) mixture is reported. The tetrachloroaurate(III) complex is extracted into butyl acetate, lithium perchlorate in methanol is added, and gold is deposited on a glassy carbon rotating disk cathode at ?0.6 V vs. SCE. The deposited gold is stripped in the same medium at a scan rate of 50 mV s^?1. The method is suitable for the determination of gold (0.1–1 mg l^?1) in chloride leach liquors.     

葡萄糖在纳米金修饰金电极上电化学行为研究

利用电还原氯金酸制备了纳米金(Nano-gold,NG)修饰Au电极。该电极对葡萄糖有催化作用,可能是由于纳米金降低了OH-表面吸附能,增加了OH-在电极表面的吸附量。通过循环伏安法研究了扫描速度、温度、本体浓度和溶液pH值对葡萄糖氧化的影响。     

Solvent extraction of gold with N-substituted benzoylthioureas

Summary Benzoylthioureas are excellent reagents for the solvent extraction of gold. Very effective separations of gold from platinum group metals and base metals are possible due to control of the extraction parameters. The best results, a fast extraction and low residual gold concentrations <1 g/l are obtained with N,N-Di-n-hexylbenzoylthiourea/toluene.     

Physical vapor deposition of one-dimensional nanoparticle arrays on graphite: seeding the electrodeposition of gold nanowires

One-dimensional (1D) ensembles of 2-15 nm diameter gold nanoparticles were prepared using physical vapor deposition (PVD) on highly oriented pyrolytic graphite (HOPG) basal plane surfaces. These 1D Au nanoparticle ensembles (NPEs) were prepared by depositing gold (0.2-0.6 nm/s) at an equivalent thickness of 3-4 nm onto HOPG surfaces at 670-690 K. Under these conditions, vapor-deposited gold nucleated selectively at the linear step edge defects present on these HOPG surfaces with virtually no nucleation of gold particles on terraces. The number density of 2-15 nm diameter gold particles at step edges was 30-40 microm-1. These 1D NPEs were up to a millimeter in length and organized into parallel arrays on the HOPG surface, following the organization of step edges. Surprisingly, the deposition of more gold by PVD did not lead to the formation of continuous gold nanowires at step edges under the range of sample temperature or deposition flux we have investigated. Instead, these 1D Au NPEs were used as nucleation templates for the preparation by electrodeposition of gold nanowires. The electrodeposition of gold occurred selectively on PVD gold nanoparticles over the potential range from 700-640 mV vs SCE, and after optimization of the electrodeposition parameters continuous gold nanowires as small as 80-90 nm in diameter and several micrometers in length were obtained.     

Preparation of polymer-protected gold/platinum bimetallic clusters and their application to visible light-induced hydrogen evolution

The dispersions of polymer-protected gold/platinum bimetallic clusters were easily and reproducibly prepared by refluxing the mixed solutions of tetrachloroaureic(III) acid and hexachloroplatinic(IV) acid in ethanol/water (1/1) at 90 ∼ 95 °C for 2 h in the presence of a protective polymer such as poly(N-vinyl-2-pyrrolidone) (PVP). The gold/platinum bimetallic clusters thus obtained were very small, well dispersed and very stable. The UV-Vis spectra and the transmission electron micrographs have indicated that each bimetallic particle has an alloy structure consisting of both gold and platinum atoms, and that the surface of the cluster particle is rich in platinum atoms and the inner core in gold atoms. The gold/platinum bimetallic clusters were used as the multi-electron redox catalysts for visible light-induced hydrogen evolution from water. The rate of hydrogen evolution depended on the mole ratio of the gold/platinum bimetallic clusters. The bimetallic clusters at the mole ratio of Au/Pt = 2/3 were the most active catalyst. The in-situ UV-Vis spectra during the reaction have indicated that the order of the aggregation in the two kinds of metal atoms is very important for structure determination of the Au/Pt bimetallic clusters. The protective polymer PVP plays a role not only in protecting hydrophobic colloidal particles in an aqueous solution, but also in determining the metal composition of the cluster surface.     

Colour reaction of gold with 5-(4-sodium sulphonatephenylazo)-8-aminoquinoline and its analytical application

The synthesis of 5-(4-sodium sulphonatephenylazo)-8-aminoquinoline (SPAQ) is described, and a simple, rapid, selective and sensitive new spectrophotometric method for determination of gold is developed. SPAQ reacts with gold(III), and in the presence of cetyl trimethyl ammonium bromide cationic surfactant and upon making the solution alkaline, forms a blue-green 1:3 (metal:ligand) with an absorption maximum at 605 nm. Beer's law is obeyed over the concentration range 0-2 microg/ml gold. The molar absorptivity and Sandell's sensitivity of the method are 1.48 x 10(5) 1.mole(-1).cm(-1) and 0.0013 microg/cm(2), respectively. The interference of various ions has been studied and the method has been used for the determination of microamounts of gold in ores and anode slimes.     

A novel fluorometric detection of Cu(2+) based on self-assembled bilayers

Fluorescent reagent sodium 1-naphthylamine diacetate (NADA) was assembled onto gold electrodes via its electrostatic interaction with cysteine (Cys) that was directly assembled on the gold electrode surface. Formation of the self-assembled bilayers was confirmed and primarily characterized by cyclic voltammetry and X-ray photoelectron spectra (XPS). The Cys modification of the gold electrode prevented direct adsorption of NADA onto the gold electrode and hence eliminated fluorescence quenching by gold. Strong fluorescence was observed from the NADA self-assembled bilayers at gold surface and was highly efficiently quenched by Cu²⁺ that allowed for an extremely highly sensitive detection of Cu²⁺ with a detection limit of 0.2 ppt and quantitative detection range of 0.5–9 ppt. The fluorescence from NADA/Cys/Au can be easily regenerated and therefore the present report showed a reusable method for immobilizing reagent in fabricating fluorescent chemosensors.     

Surface and Structural Properties of Gold Nanoparticles and Their Biofunctionalized Derivatives in Aqueous Electrolytes Solution

Gold nanoparticles reduced by sodium citrate (d ～ 10 nm) and purchased gold colloid particles (d ～ 500 nm) were examined and compared. The properties of both gold particles and their biofunctionalized derivatives with L-cysteine and L-glutathione were studied in the presence of sodium nitrate. The structural investigations indicated an aggregated inner structure.

The isoelectric points of pure gold, citrate reduced gold, and functionalized gold were measured and compared. The low isoelectric point of pure gold/water interface was explained by considering the distribution and accumulation of H⁺ and OH^? ions within the interfacial water layer, being more pronounced for OH^? ions.