Neutron activation analysis of palladium,platinum and rhodium in lead foam

The determination of palladium, platinum and rhodium in industrial concentrates such as lead foam and raw lead by neutron activation analysis is described. The noble elements are separated from the matrix by spontaneous deposition on amalgamated copper powder prior to activation. After the determination of palladium and platinum, rhodium is coprecipitated on iron hydroxide, and the precipitate irradiated for the determination of rhodium. The results are compared with those obtained by fire assay. Research Associate of I.I.K.W., Belgium.     

电感耦合等离子体原子发射光谱法测定70钛铁中锰、磷、铜、铬、镍、钼、钒和铝

提出了用电感耦合等离子体原子发射光谱法(ICP-AES)测定70钛铁中共存的8种杂质元素(锰、磷、铜、铬、镍、钼、钒、铝)。试验表明:试样宜用浓盐酸3mL及浓硝酸3mL溶解,且在制作工作曲线时应加入相同量的酸溶解基体金属(即所加入的纯铁粉和纯钛粉),所选用的8种元素的分析谱线均为检出限低、且光谱干扰小或易于扣除者。制作工作曲线时采用基体匹配法,从而消除基体干扰,方法中8种元素的检出限(3s/b)在0.002～0.02mg·mL-1范围内。按所提出方法分析了一个70钛铁标样(YSBC15602),共测定了11次,上述8种元素的测定结果与已知值相符,测定值的相对标准偏差(n=11)在0.74%～4.11%范围内。     

The determination of bromide,chloride and lead in airborne particulate matter by stripping voltammetry

Cathodic and anodic stripping voltammetry are proposed for the simultaneous determination of chloride, bromide and lead in atmospheric particulate matter. Particulate matter collected on Nucleopore membrane filters with high-volume pumps is digested in a dilute nitric acid wash at elevated temperature and pressure for 1 h. The sample is then removed to the electrochemical cell and analyzed directly for chloride and bromide by cathodic stripping and for lead by anodic stripping. The total amount of halide is first determined and then, by changing the deposition potential, the amount of bromide only is determined. The chloride is found indirectly by difference. Analysis time for the three elements is approximately 20 min beginning with a prepared sample.     

Simultaneous determination of lead,copper, and mercury at a modified carbon paste eletrode containing humic acid

The modified carbon paste electrode (CPE) responding simultaneously to lead(II), copper(II), and mercury(II) ions has been constructed by incorporating humic acid (HA) into the graphite powder with Nujol oil. Simple immerging of the electrode into the measuring solution containing these metal ions led to the chemical deposition of the ions onto the electrode through the complexation of the ions with HA. Cyclic and differential pulse voltammetry (DPV) characterized the modified electrode's surfaces. Several cyclings of the potential regenerated the electrode (from more positive than the stripping potential of reduced Hg to more negative than the reduction of Pb(II)ion), which was then used for another deposition. After five deposition/measurement/regeneration cycles, the peak current of voltammograns of the analyte decreased slightly. The response reproduced with a 5.1% relative standard deviation. We also applied ihe differential pulse technique to the previously mentioned system. Here, the detection limit tor Pb(II), Cu(II), and Hg(II) ions were 5.0 × 10⁻⁹ M 8.0 × 10⁻⁹ M, and 8.0 × 10⁻⁹ M, respectively, for 20 minutes of deposition time. After pretreatment of silver(I) ion with KC1, we could not observe any interference by other metal ions on the determination of the test ions in aqueous solution. Satisfactory results were acquired for the determination of the test metal ions in certified standard urine reference material SRM's 2670 (trace elements in urine).     

Atmospheric deposition of heavy metals in Norway studied by the analysis of moss samples using neutron activation analysis and atomic absorption spectrometry

In a study of the atmospheric deposition of trace elements in different parts of Norway, samples of the mossHylocomium Splendens were analyzed with respect to 28 elements. The determination of Cu, Zn, Cd, and Pb was carried out by atomic absorption spectrophotometry, while 24 additional elements were determined by instrumental neutron activation analysis. In samples from southernmost Norway, a substantially higher concentration was found for elements such as Pb, Sb, V, Cr, Cu, Zn, As, Se, Mo, Ag, and Cd than in samples from places located in the more northerly parts of the country. The results indicate that sources which are to the south and south-west of Scandinavia, contribute significantly to heavy metal deposition in Norway.     

An electrochemical enrichment procedure for the determination of heavy metals by total-reflection X-ray fluorescence spectroscopy

An electrolytic separation and enrichment technique was developed for the determination of trace elements by total-reflection X-ray fluorescence spectroscopy (TXRF). The elements of interest are electrodeposited out of the sample solution onto a solid, polished disc of pure niobium which is used as sample carrier for the TXRF measurement. The electrochemical deposition leads to a high enrichment of the analytes and at the same time to a removal of the matrix. This results in substantially improved detection limits in the lower picogram per gram region. The deposited elements are directly measured by TXRF without any further sample preparation step. The homogeneous thin layer of the analytes is an ideal sample form for TXRF, because scattered radiation from the sample itself is minimized. The proposed sample preparation method is useful particularly for the analysis of heavy metals in liquid samples with for TXRF disturbing matrices, e.g. sea water.     

电感耦合等离子体发射光谱法测定地质样品中K、Ca等常量元素的前处理方法对比

通过以标准物质玄武岩为试验对象,分别使用酸溶法和碱熔法进行样品前处理,采用电感耦合等离子体发射光谱法（ICP-OES）测定,二者均取得了良好的结果.其中,酸溶法对样品的消解更为彻底,元素的提取更为完全,与标准物质元素推荐值之间的误差更小.但碱熔法流程更为简单,所需时间短,且不影响样品Si元素的测定.总体来说,碱熔法适合用于常规地质样品常量元素的前处理,酸溶法适合于较难溶解的地质样品常量和痕量元素的测定.二者均对试验细节有较高的要求.实际应用中,需不断改进试验方法,严谨试验细节,以获得更简便的方法和更准确的结果.     

Elektrolytische abscheidung im hydrodynamischen system von ng-mengen eisen,kobalt, zink und wismut im graphitrohr

An electrolysis cell is described, which allows the constant-current deposition of ng amounts of elements from solutions containing less than 10 p.p.b. with yields above 98% in relative short times. Separations from elements which cannot be electrolytically deposited (e.g. Be) are possible. The electrolyte (40 ml) is cycled through a cylindrical cathode of ultrapure graphite (length 9 mm, i.d. 2.8 mm) by a PTFE-pump at 20–30 ml min^-1. A Pt/Ir (diam. 1.5 mm) anode is centered in the cathode space. The graphite cathode can be used directly for a sensitive determination of the deposited elements, e.g. by flameless a.a.s., o.e.s. (i.c.p., c.m.p.) and n.a.a. Radiotracers (⁵⁹Fe, ⁶⁰Co, ⁶⁵Zn and ²⁰⁷Bi) were used to determine the deposition yields, which were found to be optimal in NH₄F electrolytes (2–10%) of pH 5–6.     

Efficiency of sample introduction into inductively coupled plasma by graphite furnace electrothermal vaporization

A laboratory constructed graphite furnace electrothermal vaporizer (GF-ETV) was used for studying transport efficiencies. This device enables collection of the vaporization products that exit the central sampling hole of the horizontal graphite tube. For determination of the transport efficiency between the GF-ETV and the ICP-torch three methods were tested: (1) deposition of the aerosol particles and the vapour of certain elements by mixing the vaporization product with supersaturated steam and subsequent condensation (direct method); (2) dissolution of the deposited sample fraction from the interface components (indirect method); and (3) calculation from line intensities when applying GF-ETV and pneumatic nebulization sample introduction methods using mercury as a reference element. The latter, `mercury reference method' required 100% transport efficiency for mercury with the ETV, which could be approximated with the use of argon as carrier gas (without halocarbon addition). With a 200 cm³/min flow rate of internal argon in the graphite tube, the transport efficiency was between 67 and 76% for medium volatility elements (Cu, Mn and Mg) and between 32 and 38% for volatile elements (Cd and Zn). By adding carbon tetrachloride vapour to the internal argon flow, the transport efficiency increased to 67–73% for the five elements studied.     

The application of electrodeposition techniques to flameless atomic absorption spectrometry : Part IV. Separation and preconcentration on graphite

A new flameless atomic absorption technique for the determination of trace metals in a salt matrix is described. The elements to be determined are electrolyzed on to a graphite electrode, the exposed part of which is ground, and a portion of the graphite powder is finally analyzed directly by flameless atomic absorption in a graphite furnace. Many elements can be determined from a single electrochemical deposition. The graphite powder may also be stored for later control analysis. The effects of various experimental parameters are described. The method is applied to the determination of trace metals in commercial salts.     

Determination of B1 2, iodine,iodochlorhydroxyquin, liothyronine,thyroxine and zinc sulfate in drugs by neutron activation analysis

Instrumental neutron activation analysis was used in this study for the determination of the elements cobalt, iodine, and zinc in pharmaceutical dosage forms in order to develop a simple, fast and accurate method for their quantitation in these products. It appears that this procedure could be established as an official method for the determination of the elements iodine and zinc in drugs, in which these are present as active ingredients. Also it could be employed as an alternative technique of the officially used methods for the determination of B_{1 2}, iodochlorhydroxyquin, liothyronine, thyroxine and other substances with pharmaceutical interest, containing these elements in their molecules.     

Electrodeposition studies of rare earths

The combination of neutron activation analysis (NAA) and electrochemistry has been used to study the deposition behavior of rare earth elements, as it is reported that excepting La, no other rare earths are electrodeposited. The radiotracers of rare earth elements were electrolyzed in an aqueous medium on a graphite electrode by varying the voltage and time of electrodeposition, thereby optimizing the final experimental conditions for quantitative deposition of rare earth elements. The observations are reported in this work.     

Problems,possibilities and limitations of inductively coupled plasma atomic emission spectrometry in the determination of platinum,palladium and rhodium in samples with different matrix composition

The economic and geological importance of platinum group of elements has led to the development of analytical methods to quantify them in different types of samples. In the present paper the quantitative information for spectral interference in radial viewing 40.68 MHz inductively coupled plasma atomic emission spectrometry in the determination of Pt, Pd and Rh in the presence of complex matrix, containing Al, Ca, Fe, Mg, Mn, P and Ti as matrix constituents was obtained. The database was used for optimum line selections. By using the selected analysis lines the following detection limits in ng g^− 1 were obtained: Pt 1700, Pd-1440, Rh-900. The reached detection limits determine the possibilities and limitation of the direct ICP-AES method in the determination of Pt, Pd and Rh in geological and environmental materials. The database for spectral interferences in the presence of aluminum can be used for the determination of platinum group of elements in car catalysts.     

Determination of Gold, Silver, and Copper in Gold-Base Alloys by Potentiostatic Coulometry

The working conditions for the simultaneous coulometric determination of 0.5 to 3 mg of gold, silver, and copper with a relative standard deviation of at most 0.5% were found in the study of the voltammetric behavior of Au(III), Ag(I), and Cu(II) at a platinum electrode in a 2 M HCl + 0.1 M KCNS solution. Fivefold mass amounts of gold with respect to silver and copper did not interfere with their determination. The three elements can be triply determined in a single portion of a solution using the alternate cathodic and anodic polarization of the electrode ensuring the complete deposition and stripping of Au(0) and Ag(0) and the complete reduction and oxidation of Cu(II) Cu(I). The mechanism of current formation due to the chemical reaction of Au(I) disproportionation and its effect on the results of gold determination were studied using the current–time curves. Experimental conditions were proposed to eliminate this reaction. The procedure was used for determining the composition of ternary jewelry alloys containing different amounts of gold, silver, and copper without their preliminary separation.     

Developing electrodeposition techniques for preconcentration of ultra-traces of Ni, Cr and Pb prior to arc-atomic emission spectrometry determination

Electrodeposition is known to be proper for separation and preconcentration of extremely low concentrations of analytes from the bulk sample which is instrumentally very simple. In the present research, a combination of electrodeposition with arc atomic emission spectrometry (ED-AAES) method has been developed in order to improve the analytical performance of this spectrometry technique. The results show that sensitivity and detection limits by using ED-AAES were improved 1000–2000 folds over those of normal arc atomic emission spectrometry in determination of the selected elements. The detection limits for measurement of Ni, Cr and Pb were 2.56, 3.05 and 2.11 µg L^{− 1} for monodeposition and 3.31, 3.72 and 3.25 µg L^{− 1} for simultaneously deposition, respectively. The precision of determination was in the range of 2–4% RSD. Typical calibration graphs for these elements were linear up to 100 µg L^{− 1}, depending on the element and matrix.Application of this technique was also tested on determination of the studied elements in an electroplating plant's waste water. The accuracy of technique was verified by comparing the results of the waste water analysis with those of electrothermal atomic absorption spectroscopy as a reference standard method.The obtained results show that the combined technique (ED-AAES) has been progressed substantially toward the ultimate goal of direct interference-free determination of trace analysis in complex samples by AAES.     

Development and characterization of ZnO, Au/ZnO and Pd/ZnO thin films through their adsorptive and catalytic properties

In this paper, we report (a) the development of ZnO thin films prepared by pulsed laser deposition and partially covered with nano-particles Pd or Au and (b) their physicochemical study, in order to investigate their catalytic and/or adsorptive properties. It is the first time where two different and popular methods, namely pulsed laser deposition and reversed flow-inverse gas chromatography, are combined. The inverse gas chromatographic technique with the corresponding time-resolved analysis is used for the first time in order to characterise compounds in the nano-scale domain. We focus on the determination of physicochemical quantities mainly concerning the adsorption in thin films, with (Pd/ZnO) or without (Au/ZnO) catalytic behaviour. Thus, entropy and other important physicochemical quantities are calculated which reveal the mechanism of adsorption as well as of isomerization-hydrogenation of 1-butene and contribute to the study of heterogeneity of thin film surfaces. The programs used have been written in Fortran. An important achievement is also the determination of the standard deviations of the kinetic constants.     

Trends in the Development of the Potentiostatic Coulometry of Inorganic Substances

The published data on the application of potentiostatic coulometry to the determination of inorganic substances published in 1986–2002 have been analyzed and generalized. The following new trends in the development of potentiostatic coulometry have been distinguished: the precise (at a level of a tenth of a percent and lower) determination of large amounts of elements, the determination of elements in different oxidation states in the presence of each other, detection in flow systems and in ion chromatography, and the determination of two and more components in a single sample. By now, about 70 elements can be determined in different samples by potentiostatic coulometry.     

轻稀土元素La、Pr、Nd、Sm的同时光度法测定

本文提出以各因素同时改进的因素轮换法来处理多组份混合物溶液的吸收光谱,方法能对任一组份加以任意的约束,因而适用于“病态体系”。用两种显色体系的数据联合解矛盾方程,进行La、Pr、Nd、Sm四组份的同时测定,计算得到满意的结果。     

Anodic Stripping Voltammetry of Heavy Metals at Nanocrystalline Boron‐Doped Diamond Electrode

Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD.     

电感耦合等离子体发射光谱法测定二次电池废料中锂、镍、钴、锰的含量

采用HCl-HNO 3溶解样品,使用电感耦合等离子体发射光谱(ICP-OES)法直接测定二次电池废料中含量低于20%的锂、镍、钴和锰的含量。选用元素最佳分析谱线和仪器合适的工作条件测定实际样品,实验结果表明共存元素对测定结果基本没有影响。相对标准偏差(n=11,RSD<2%)。通过不同方法的测试结果对比,同一样品的不同测定结果基本吻合,结果表明,方法操作快速简便,分析结果准确,能够满足二次电池废料中20%以下的锂、镍、钴和锰的测定。