Determination of lead(II) by argentimetry

A titrimetric method for determination of lead(II), based on the reaction between plumbite and silver ions, is described. Sodium hydroxide solution is added to the sample until the precipitate of lead hydroxide has redissolved. The solution is then made 0.025M in sodium chloride and titrated with silver nitrate. The titration is monitored with a silver electrode. An error smaller than 0.5% has been obtained for 0.05M lead (II).     

氢化物发生-分光光度法连续测定砷和铅

本文提出了以氢化物与硝酸银反应为基础的在一份试样溶液中连续测定微量砷和铅的分光光度法。利用硝酸银-聚乙烯醇-乙醇溶液吸收砷化氢显色测定砷,硝酸银-明胶-乙醇溶液吸收铅化氢显色测定铅。方法灵敏快速,通过稀释有色吸收液可测定砷与铅含量相差较大的样品。应用于沉积物和土壤中砷和铅的分析,获得满意的结果。     

Complex citrates of metals in Inorganic Analysis : Some preliminary observations and the application of citrate complex formation in the qualitative analysis of the metallic ions of the Silver group

The use of sodium citrate as a reagent for the separation of silver group metals has been described. Silver, lead and mercurous ions are all capable of forming soluble citrate complexes, but they differ in their stability. The lead complex is not decomposed by soluble chlorides, whereas silver and mercurous complexes yield the insoluble chlorides. The fact that lead sulphate is soluble in a hot solution of sodium citrate has been utilized for the detection of lead, when present as insoluble sulphate, in a mixture.     

Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration.     

Transmetalation reaction between hydrophobic silver nanoparticles and aqueous chloroaurate ions at the air-water interface

The transmetalation reaction between a sacrificial nanoparticle and more noble metal ions in solution has emerged as a novel method for creating unique hollow and bimetallic nanostructures. In this report, we investigate the possibility of carrying out the transmetalation reaction between hydrophobic silver nanoparticles assembled and constrained at the air-water interface and subphase gold ions. We observe that facile reduction of the subphase gold ions by the sacrificial silver nanoparticles occurs resulting in the formation of elongated gold nanostructures that appear to cross-link the sacrificial silver particles. This transmetalation reaction may be modulated by the insertion of an electrostatic barrier in the form of an ionizable lipid monolayer between the silver nanoparticles and the aqueous gold ions that impacts the gold nanoparticle assembly. Transmetalation reactions between nanoparticles constrained into a close-packed structure and appropriate metal ions could lead to a new strategy for metallic cross-linking of nanoparticles and generation of coatings with promising optoelectonic behavior.     

The adsorption of silver on potassium cyanocobalt(II)ferrate(II)

A procedure is described for recovering silver from industrial sewage (mining and photo-industry etc) with the aid of the ion-exchanger potassium cyanocobalt(II)ferrate(II) (KCFC). Silver is easily removed by simple mixing with KCFC, even from solutions containing less than 1 g of silver per ton of solution. The process is performed at room temperature at pH < 7. There is no interference from a 600-fold amount of Ca, Cu(II), Zn, Cd, Pb, and Fe(II). Pure silver may be obtained by dissolution of the ion-exchanger in potassium cyanide solution, subsequent precipitation as sulphide, and roasting, or by melting it out of the ion-exchanger after heat treatment in a high-frequency furnace. With 1 kg of KCFC, 1.25 kg of silver may be extracted from solution. The process is simple and economic.     

New trends in the chemistry of iron(III) citrate complexes: correlations between X-ray structures and solution species probed by electrospray mass spectrometry and kinetics of iron uptake from citrate by iron chelators

Despite the crucial role of "iron(III) citrate systems" in the iron metabolism of living organisms (bacteria as well as plants or mammals), the coordination chemistry of ferric citrate remains poorly defined. Variations in the experimental conditions used for the preparation of so-called ferric citrates (iron salt, Fe:cit molar ratio, base, pH, temperature, solvent) lead to several different species, which are in equilibrium in solution. To date, six different anionic complexes have been structurally characterized in the solid state, by ourselves or others. In the work described herein, we have established the experimental conditions leading to each of them. Five were obtained from aqueous solution. With the exception of a nonanuclear species (of which fragments have been detected), all were identified in aqueous solution on the basis of electrospray ionization mass spectrometry. In addition, the spectra revealed a new trinuclear species, which could not be crystallized. Kinetic studies of iron uptake from citrate species by iron chelators confirmed the results indicated by the ESI-MS studies. These studies also allowed the relative molar fraction of mononuclear versus polynuclear complexes to be determined, which depends on the Fe:cit molar ratio.     

Lead contents of foodstuffs

Some possible errors are pointed out, which can occur in the determination of lead and a method is described which minimizes these errors. The loss of lead during the dry-ashing-procedure was determined in dependence on the temperature in the sample measured by immersed thermocouples. It is not advisable to transfer ashing data from one foodstuff (e.g. vegetable) to foodstuffs of different composition (e.g. meat); such data must be determined experimentally. Many matrix elements in ash solutions influence the lead determination by atomic absorption spectroscopy. By H₂S coprecipitation of lead and added silver ions as PbS/Ag₂S this disturbance can be avoided and the lead concentration is simultaneously increased. With the aid of a nitrate-carbonate melt before the H₂S coprecipitation the residual carbon of the ash is removed and acid-insoluble compounds are made accessible. The use of hydrofluoric acid for destroying the silicates, which is disadvantageous, can thus be omitted. The lead content in the final solution is determined in an atomic absorption spectrometer by comparison with a standard solution of appropriate concentration.     

Tetrabromophenolsulphonphthalein as Adsorption Indicator : Volumetric estimation of Silver and Thallium

1.The estimation of iodide and bromide ions in ammoniacal solutions has been described using bromophenol blue as adsorption indicator and the theory of the adsorption indicators has been briefly discussed in the light of the observations. 2.A method has been described by which the silver and thallium ions can be estimated in presence of each other.     

The accurate determination of gold and silver in ores and concentrates by wet-chemical analysis of the lead assay button

Hydroquinone or formic acid can be used as reductant for the quantitative precipitation of gold in the lead perchlorate solution obtained after the lead assay button has been parted with perchloric acid. Silver chloride can be completely precipitated by dilution and overnight standing of the parting solution, thus both gold and silver can be isolated by filtration for the final measurement. The proposed lead-wet chemical method was successfully applied to ores, concentrates, dusts, etc.     

Direct stripping voltammetric determination of lead,cadmium and zinc dithizonates

A procedure is described in order to determine lead, cadmium and zinc dithizonates by stripping voltammetry. The polarographic analysis is performed in a medium of methanol and benzene (chloroform) in a ratio of 7:1 and in the presence of silver dithizonate. Sodium nitrate was used as a base electrolyte. By carrying out these analytic conditions it is possible to perform directly the stripping voltammetric analysis in benzene (chloroform) solution of extracted dithizonates, without further treatment. Silver nitrate in methanol is added to dithizonates in order to free lead, cadmium, and zinc from their complexes, to be determined polarographically.     

Highly selective and sensitive spectrophotometric determination of trace amounts of silver ion in surfactant media using 2-mercaptobenzoxazole

A simple and accurate spectrophotometric method for determination of trace amounts of silver ion in tap and wastewater solution and photographic solutions has been described. The spectrophotometric determination of silver ion using 2-mercaptobenzoxazole (MBO) in the presence of Triton X-100 as nonionic surfactant has been carried out. The Beer's law is obeyed over the concentration range of 0.1-9.0 microg mL(-1) of Ag+ ion with the detection limits of 1.6 ng mL(-1). The influence of type and amount of surfactant, pH, complexation time and amount of ligand on sensitivity of method were optimized. Finally the repeatability, accuracy and the effect of interfering ions on the determination of silver ion were evaluated. There is a good agreement between results of proposed method and atomic absorption spectrometry.     

Flame atomic absorption spectrometric determination of silver after preconcentration on Amberlite XAD-16 resin from thiocyanate solution

A method of silver preconcentration by using a column containing Amberlite XAD-16 resin and this future determination by a flame AAS after elution is proposed. The effect of the factors such as pH, the nature of complexing agent, sample volume, flow rate, the type and concentration of elution solution on the preconcentration efficiency have been investigated. The influence of some matrix elements on the recovery of silver were also examined. It was found, that the quantitative recovery of thiocyanate complex of silver was obtained from nitric acid solution (pH 2) as 99.20+/-0.07% at the 95% confidence level. A preconcentration factor up to 75 could be obtained. The detection limit of silver was 0.047 mg l(-1). The adsorption of silver onto Amberlite XAD-16 can be formally described by a Langmuir equation with maximum adsorption capacity 4.66 mg g(-1) (0.043 mmol g(-1)). The proposed method was applied to determination of silver in standard alloy with relative error 6.25%.     

火试金法测定铅冶炼渣中的金、银含量

建立了铅冶炼渣中的金银含量的测定方法,采用火试金法富集铅冶炼渣中的金、银,铅扣经灰吹后,形成金银合粒,合粒中除有金银外,还残留微量的铅铋杂质,合粒经硝酸分金后,实现金银分离,得到金粒和分金溶液。合粒中杂质保留在分金溶液中,分金溶液经酸处理,采用电感耦合等离子体发射光谱(ICP-OES)法测定其中杂质量和微量的金量。金粒质量补正分金溶液中微量金量即为样品中的金量,合粒质量减去金粒质量和杂质量即为银量。ICP-OES法测定杂质解决了合粒中铅铋残留和分金失误造成微量金进入分金溶液现象。方法精密度较好,加标回收率分别为银98.6%～100%,金96.2%～102%。方法准确、方便、快捷,能很好地满足铅冶炼渣中金、银含量的测定。     

Potentiometric determination of Silver (I) by potassium iodate

Summary A potentiometric method has been described for the determination of Silver(I) using standard Iodate solution with pure metallic silver plate as the indicator electrode. Accurate results have been obtained at as low as 0.001 M silver solutions.     

火试金法测定铅冶炼渣中的金、银含量

建立了铅冶炼渣中的金银含量的测定方法,采用火试金法富集铅冶炼渣中的金、银,铅扣经灰吹后,形成金银合粒,合粒中除有金银外,还残留微量的铅铋杂质,合粒经硝酸分金后,实现金银分离,得到金粒和分金溶液。合粒中杂质保留在分金溶液中,分金溶液经酸处理,采用电感耦合等离子体发射光谱(ICP-OES)法测定其中杂质量和微量的金量。金粒质量补正分金溶液中微量金量即为样品中的金量,合粒质量减去金粒质量和杂质量即为银量。ICP-OES法测定杂质解决了合粒中铅铋残留和分金失误造成微量金进入分金溶液现象。方法精密度较好,加标回收率分别为银98.6%～100%,金96.2%～102%。方法准确、方便、快捷,能很好地满足铅冶炼渣中金、银含量的测定。     

Voltammetry using a dental amalgam electrode for heavy metal monitoring of wines and spirits

We have introduced a non-toxic electrode material similar to dental amalgam for use in voltammetry. Its electrochemical properties are like a silver electrode. However, it possesses a higher overvoltage towards hydrogen than silver, and therefore enables detection of metals like zinc, nickel and cobalt. As such solid electrodes are found to give stable results over several weeks, without any maintenance, and because this method greatly facilitates monitoring of heavy metals, attempts to apply such methods to various samples have been are carried out. The present paper deals with the determination of zinc and lead at nanogram per milliliter levels in wines and spirits with only minor treatment of the samples. The procedure may easily be adapted to continuous monitoring.We have previously found that audible sound may greatly increase the voltammetric signal using liquid mercury as well as silver as electrode material. This is also applied to the actual systems.Finally, model determinations of thallium in brandy with the dental amalgam electrode are compared with atomic absorption spectrometric (AAS) measurements. It was found that the electrode could be used repeatedly, without fouling, and with results close to those found by the AAS method.     

痕量银的催化动力学测定法研究

研究了在稀硫酸溶液中,在Ag⁺的存在下,K₄Fe(CN)₆和o-Phen的反应(银的新指示反应),反应机理为并用此来测定痕量银。根据Arrhenius方程式计算了催化和非催化反应的活化能,分别为64.15KJ/mol和96.89KJ/mol。本方法灵敏度为8×10^-12g·ml^-1,且选择性好。测定地质样品结果满意。平均标准偏差为0.024,变动系数2.43%。     

Side effects in measurements of selectivity coefficients of solid state ion selective electrodes

The influence of various factors such as solubility, the oxidation of the membrane, and the contamination of the solution, on the experimental values of the selectivity coefficients of solid state sulphide ion selective electrodes is discussed. A new method for the evaluation of very small selectivity coefficients, based on the addition of reagents forming complexes or insoluble salts with the main ion, is proposed. By means of this method, selectivity coefficients for silver, copper, cadmium and lead ion selective electrodes have been determined, which are in far better agreement with thermodynamic values than those described in the literature.     

Cyclotron isotopes and radiopharmaceuticals XXVI. A carrier-free separation of77Br from se

A silver chloride co-precipitation and ion exchange separation method is described for the carrier-free isolation of⁷⁷Br bromide from isotopically enriched⁷⁷Se targets following dissolution of the irradiated⁷⁷Se in nitric acid. A cation exchange procedure has been devised to remove the silver and yield a dilute hydrochloric acid solution containing ≈90% of the precipitated⁷⁷Br as bromide. The radiochemical and chemical composition of several preparations have been analyzed. A method for the quantitative recovery of the isotopically enriched selenium is described. Research carried out under contract with the U.S. Department of Energy and supported by its Division of Basic Energy Sciences. Supported in part by the Massachusetts Heart Association and by NIH Grant No. HL 18487-01. All inquiries should be directed to R. M. Lambrecht. For earlier papers in this series see Ref.¹²