Ion-selective electrodes for gold and silver determination

Some new ion-selective electrodes for silver and gold are described. They are based on the ion-associate species formed by the cyanide, chloride or thiourea complexes of the metals, with hydrophobic anions or cations, as appropriate. The electrodes have been applied to the determination of gold and silver in various technological process solutions in industry.     

Spectrochemical determination of impurities in telluric acid

An emission spectrographic method is described for determination of 20 elements present as impurities in telluric acid. Samples are excited in a 12-A. d.c. arc with the use of NaCl-KCl as a spectrographic buffer and germanium as internal standard. The limit of determination lies between 10(-5) and 10(-2)%. The precision of the method calculated as relative standard deviation is 10-25%.     

Spectrochemical determination of germanium in tar ashes

A technique for the emission spectrographic determination of germanium in tar ashes is described. Internal standardization was employed, Ge 2651.178 Å and Fe 2645.427 Å being the analysis pair. The effects of varying matrix were diminished by making up the Fe contents of the samples to a convenient limit, and by the addition of calcium carbonate. The technique, applicable to materials of reasonably different matrices, gives a precision of the order of 8–9%, expressed as standard deviation.     

直接灰吹法测定金泥中金和银的研究

通过对铅捕集贵金属原理的研究,首次提出铅覆盖再次富集的概念,建立了高品位金泥中金、银的检测方法。以经典火试金法测得的金银含量为准确值,计算金泥直接灰吹对金银的回收率,探讨了铅箔用量、称样量、灰吹温度和铅箔覆盖方式对金银回收率的影响,获得了高品位金泥直接灰吹的最佳工艺条件。在最佳工艺条件下,对氰化-置换得到的高品位金泥进行直接灰吹法与火试金方法对比试验,结果显示直接灰吹法的分析结果与火试金重量法结果相吻合。 金的回收率为99.84-100.12%,RSD≤0.10%(n=6),银的回收率为99.41-100.66,RSD≤0.40%(n=6)。该方法操作简便、快捷准确,劳动强度低,有很好的适用性。     

Core-satellites assembly of silver nanoparticles on a single gold nanoparticle via metal ion-mediated complex

We report core-satellites (Au-Ag) coupled plasmonic nanoassemblies based on bottom-up, high-density assembly of molecular-scale silver nanoparticles on a single gold nanoparticle surface, and demonstrate direct observation and quantification of enhanced plasmon coupling (i.e., intensity amplification and apparent spectra shift) in a single particle level. We also explore metal ion sensing capability based on our coupled plasmonic core-satellites, which enabled at least 1000 times better detection limit as compared to that of a single plasmonic nanoparticle. Our results demonstrate and suggest substantial promise for the development of coupled plasmonic nanostructures for ultrasensitive detection of various biological and chemical analytes.     

Trace metal determination in animal tissues: an interlaboratory comparison

Two dried and powdered preparations of narwhal liver and muscle were distributed to 13 laboratories for analysis for Cu, Cd, Zn, Pb, Hg, and Se. Laboratories chose their own methods, using atomic-absorption spectrometry, atomic-emission spectrometry with a direct-current or inductively-coupled plasma, anodic stripping voltammetry (ASV), neutron activation analysis (NAA), and gas chromatography. The coefficients of variation ranged from 2 to 5% for Cu, Cd, Zn, Hg in liver, but were somewhat higher for Zn by ASV and NAA. In muscle, the precision for Zn was similar to that for liver, but was poorer for Cu (8.8%) and Cd (19%). For Pb, the overall precision was 15% and 21% for liver and muscle respectively. Selenium in both tissues was determined with an overall precision of 6-7%, except by NAA, for which it was considerably worse, at 21-26%.     

电位滴定法测定火试金得到的金银合粒中的银

本文研究了用自动电位滴定仪测定外购铜物料样品中经火试金熔炼、富集、灰吹后得到的金银合粒中银的方法。金银合粒用硝酸溶解后在自动电位滴定仪上用硫氰酸钾标准溶液滴定银量,选择了仪器的测定条件,考察了溶液酸度、共存元素对测定的干扰。方法相对标准偏差为1.34％～3.62％,测定结果与硫氰酸钾手工滴定法和减杂法相一致。方法的准确度和精密度均能满足分析需要,具有较强的实用性和推广价值。     

Spectrochemical determination of tungsten and boron in mineral matrix

The spectrochemical behavior of nonvolatile tungsten and boron was tested by adding different buffers and using 12 A ac arc excitation. The oxidization and sulfidization processes were found to be most effective for facilitating the volatilization. The optimal admixture was the copper oxide buffer for both the detection limit and the precision of the method. The reference values of the background or a palladium line blackening were used.     

Biamperometric determination of copper,silver and gold with ascorbic acid

The simultaneous determination of milligram amounts of copper, silver and gold in mixtures is described. Ascorbic acid is added in excess and back-titrated biamperometrically with standard potassium iodate solution. Mixtures can be analyzed by using precipitation and masking     

Enzymeless determination of cholesterol using gold and silver nanoparticles as electrocatalysts

We present the results of synthesis and study of the electrocatalytic activity of gold and silver nanoparticles of different composition (individual metals, core–shell particles, nanoalloys, and particles synthesized electrochemically), immobilized on the surface of a glassy carbon electrode, with respect to cholesterol. A surfactant (cetyltrimethylammonium bromide) is selected to create an aqueous–organic emulsion of cholesterol. It is demonstrated that nanoparticles with a gold core and a silver shell with the regression equation of I = 1.4 × 10^–5 c _chol + 5.8 × 10^–5 (R ² = 0.97) and silver nanoparticles synthesized electrochemically with the regression equation of I = 1.0 × 10^–5 c _chol + 3.0 × 10^–4 (R ² = 0.95) possess optimal electrocatalytic characteristics.     

Recent developments in the determination of gold by atomic spectrometry techniques

Determination of gold in different kinds of samples is often a challenging task for analysts. Its concentration is usually very low and the sample matrix may cause serious interferences during measurement. Therefore, preconcentration and separation methods should be used to solve these problems and render more sensitive, accurate and interference-free determination. The recent developments in sample treatment, such as liquid and solid phase extraction, coprecipitation and electrodeposition, are presented. In addition, important extension and improvements in atomic spectrometry techniques — mainly electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry, are discussed.     

Epitaxial growth of heterogeneous metal nanocrystals: from gold nano-octahedra to palladium and silver nanocubes

With octahedral Au nanocrystals as seeds, highly monodisperse Au@Pd and Au@Ag core-shell nanocubes were synthesized by a two-step seed-mediated method in aqueous solution. Accordingly, we have preliminarily proposed a general rule that the atomic radius, bond dissociation energy, and electronegativity of the core and shell metals play key roles in determining the conformal epitaxial layered growth mode.     

The simultaneous determination of gold and silver in blister copper and speiss products

A method for determination of silver and gold (concentration ranges of 0.1–0.4% and 8·10^–4–3·10^–3% respectively) in blister copper and speiss is described. Silver is determined directly in the solution after dissolution of the sample and appropriate dilution. The amount of gold is determined in an aliquot of the same solution after extraction with methyl isobutyl ketone. The relative standard deviation of the method described is 3.3% for speiss and 4.4% for blister copper for gold and 1.6% and 2.5% for silver respectively.     

Electrolytic investigations : Electrolytic determination of silver after a silver chloride precipitation

A procedure is described for determining silver electrolytically after first precipitating the silver as silver chloride. The silver chloride is filtered through a filter paper, and the filter paper and precipitate are treated with a mixture of perchloric, sulfuric, and nitric acids. The solution is then evaporated to fumes of sulfuric acid, and the silver determined electrolytically by the cyanide method.     

Removal of dissolved oxygen from water: A comparison of four common techniques

Four common techniques for the removal of dissolved oxygen from water have been examined: boiling at 1 atm, boiling under reduced pressure, purging with N(2) and sonication under reduced pressure. After treatment, the residual oxygen in solution was analysed by the Winkler method. Nitrogen purging for 20-40 min at flow rate of 25 mL/s was found to be the most effective oxygen removal method. Boiling at 1 atm was found to be the least effective. None of the techniques evaluated here lead to complete removal of oxygen. The concentration of residual dissolved oxygen after purging for 20-40 minutes with nitrogen is 0.2-0.4 ppm.     

时间分辨化学发光分析的研究 I: 金和银的同时化学发光测定

本文根据Luminol-K2S2O8体系中Au(III)和Ag(I)化学发光动力学性质的不同, 建立了金和银的时间分辨化学发光分析法, 研究结果表明, 利用时间分辨化学发光分析法同时测定混合物中多组分是可行的.     

Spectrochemical and thermal analysis of Al-tetrabromophthalate and tetrabromophthalic anhydride. A comparison of methods for determination of aluminium

A sequential inductively coupled plasma atomic emission spectrometer (ICP-AES) was used to determine Al content in Al-tetrabromophthalate (Al-TBP). Four emission lines of Al (I) at 309.271, 396.152, 308.215 and 394.401 nm were compared. The microwave mineralisation was carried out by using a two-step digestion procedure and HNO(3)-H(2)SO(4). The thermal analysis of Al-TBP and tetrabromophthalic anhydride (TBPA) was performed in the air atmosphere. Statistical tests applied (t-test, F-test) showed no significant differences between the Al results obtained by ICP-AES and thermal method of analysis.     

Spectrochemical determination of rare- earth metals in uranium and its salts

An emission spectrographic procedure is described for the determination of 0.05-4 ppm of rare-earth metals in uranium metal and its salts. Uranium is extracted from the sample with tributyl phosphate, and the impurities are separated by precipitation as hydroxides and oxalates, with yttrium as a carrier. After conversion into the oxides, the rare-earth metals are mixed with graphite and excited in a d.c. arc.     

Effect of the metal nature on hemostatic activity of water-soluble gold and silver nanocomposites

The hemostatic activity of polymeric gold and silver nanocomposites depends on their kinetic stability caused by the interaction of the ligand with nanoparticles. The properties of the nanoparticles are determined by the metal nature.