Determination of palladium, platinum and rhodium in geologic materials by fire assay and emission spectrography

A method is described for the determination of palladium down to 4ppb (parts per billion, 10(9)), platinum down to 10 ppb and rhodium down to 5 ppb in 15 g of sample. Fire-assay techniques are used to preconcentrate the platinum metals into a gold bead, then the bead is dissolved in aqua regia and diluted to volume with 1M hydrochloric acid. The solution is analysed by optical emission spectrography of the residue from 200 mul of it evaporated on a pair of flat-top graphite electrodes. This method requires much less sample handling than most published methods for these elements. Data are presented for G-1, W-1, and six new standard rocks of the U.S. Geological Survey. The values for palladium in W-1 are in reasonable agreement with previously published data.     

Spectrophotometric determination of indium in nickel alloys and zinc ores with 1-(2-pyridylmethylideneamine)-3-(salicylideneamine)thiourea

A sensitive method for the spectrophotometric determination of indium with 1-(2-pyridylmethylideneamine)-3-(salicylideneamine)thiourea is proposed. A yellow complex is formed at pH 4.5 (succinate buffer) in a medium containing 40% dimethylformamide, and the absorbance is measured at 415 nm. The molar absorptivity is 6.2 x 10(4)l.mole(-1).cm(-1). The relative standard deviation of the procedure is 1.5%. The method has been applied to determination of indium in a nickel alloy and three zinc ores, with prior isolation of indium by co-precipitation with ammonia and extraction into n-butyl acetate from 5M hydrobromic acid.     

Polarographic determination of indium(III) after salting-out extraction of the bromide complex into acetonitrile

A simple and sensitive method has been developed for the polarographic determination of indium(III) after solvent extraction into acetonitrile, salted-out from aqueous solution with sodium bromide. The extracted indium(III)-bromide complex gives a well-defined d.c. wave with E(1 2 ) = -0.69 V vs. SCE. The wave-height is directly proportional to the concentration of indium(III) from 1.6 x 10(-6) to 3.0 x 10(-4)M with respect to the original aqueous solution. In the a.c. polarographic method, a linear calibration curve is obtained for indium(III) over the concentration range from 1.6 x 10(-6) to 1.5 x 10(-5)M, and interference from most foreign ions can be eliminated. In particular, 10.0 mg of Fe(III) and 2.5 mg of Tl(III) are tolerated when 1.0 g of ascorbic acid is added. The lower limit of determination is 8 x 10(-8)M indium(III) by the square-wave polarographic method.     

A well-tested procedure for instrumental neutron activation analysis of silicate rocks and minerals

Procedures for instrumental neutron activation analysis (INAA) have been developed and used on more than a thousand small samples of terrestrial and lunar silicate rocks and minerals for determination of Co, Cr, Fe, Hf, Na, Ni, Sc, Ta, Th, and the rare earths La, Ce, Sm, Eu, Tb, Yb, and Lu. Precision has been determined by repeated analysis of Knippa basalt and DTS-1 to be better than ±5 percent for all elements except Ni, Yb, Lu, and Hf. Mean values and estimates of accuracy are given for Knippa basalt and USGS standards AGV-1, G-2, GSP-1, and W-1. Important features of the method are its precision and ease of data reduction.     

The determination of rubidium by the method of stable isotope dilution

The rubidium contents of a granite (G-1), a diabase (W-1) and sea-water have been determined by mass spectrometric isotope dilution analysis. The values found are: G-1, 214 p.p.m-; W-1, 21.3 p.p.m.; sea water, 121.4 μg/l. These results show excellent agreement with values obtained at Harwell by neutron activation analysis, and the coefficient of variation for four determinations is usually ±1–2%.Rubidium ions were produced in the mass spectrometer by either a side filament or a centre filament technique. The former method enables rubidium and lithium determinations to be combined; the results obtained by the second method suggest that concentrations of the order of 1 p.p.m. may be determined for a sample of only a few mg with little chemical treatment beyond that required to decompose the sample.     

Determination of indium and tin by activation analysis using replacement substoichiometry

A new method for the determination of indium by activation analysis has been developed. It is based on the replacement of indium from indium dithizonate (in carbon tetrachloride) by a substoichiometric amount of aqueous mercury(II) solution. Preliminary steps are the extraction of indium from alkaline cyanide solution with an excess of dithizone solution and washing the extract with buffer solution. The time necessary for the separation is 10-20 min. With this method indium can be determined by using either short ((116m)In, t(1 2 ) = 54 min) or long-lived radioisotopes ((114m)In, t(1 2 = 50 d). As by the reaction (112)Sn (n, gamma)) (113)Sn (119d) --> (113)In (104 min), indium-113m is formed, which has a different gamma-spectrum from that of indium-114m, the determination of both indium and tin is possible. The proposed method has been applied to the determination of indium and tin in granite and gallium.     

Voltammetric determination of indium in alumina supported catalysts

A sensitive and rapid method for the estimation of trace levels of indium in alumina supported catalysts using square wave voltammetry (SWV) is discussed. The SWV method for indium in the alumina matrix is standardized using synthetic samples and good recoveries were obtained. Calibration graphs are linear in the range 1-5 mug/ml and the detection limit is 3.57 x 10(-8) g/ml. In order to determine the accuracy of the proposed method, the results obtained have been compared with those given by atomic absorption spectrophotometry (AAS). Statistical analysis shows no significant bias between the two methods. This technique is found suitable for the estimation of indium in the range 0.1-1.0% (w/w) in the catalyst samples with an RSD < 1.5%.     

氢化物发生-原子荧光光谱法同时测定高纯铟中As、Sb

研究了氢化物发生-原子荧光光谱法测定高纯铟中微量As、Sb元素的条件,选择了适宜的反应条件以及仪器的最佳工作条件,考察了铟基体对被测元素的干扰,采用基体匹配的方法消除干扰,建立了氢化物发生-原子荧光光谱法测定高纯铟中微量的As、Sb的分析方法。As、Sb的检出限分别为0.18和0.28 ng/mL,测定下限为1.2×10-5和1.9×10-5,相对标准偏差分别为1.9%和1.7%,回收率为97.4%和103%,适用于5～6 N高纯铟中微量As、Sb的测定。     

Substoichiometric determination of traces of palladium by neutron-activation analysis

A highly selective, rapid one-step radiochemical separation procedure for palladium has been developed. It is based on the solvent extraction of palladium diethyldithiocarbamate from a 5M hydrochloric acid solution with a substoichiometric amount of copper diethyldithiocarbamate in chloroform. The separation has been applied to the determination of traces of palladium by neutron-activation analysis, in platinum, the rocks W-1 and PCC-1 and a biological material (kale). Amounts of palladium down to 10(-8) g have been determined.     

The determination of bromine in rocks by neutron activation analysis

A neutron activation method for the determination of bromine in rocks and minerals is described. After removal of iodine, bromine is separated by oxidation with potassium permanganate and extraction with carbon tetrachloride. Bromine is thon precipitated as silver bromide; yields are from 60 to 84%. The method has a sensitivity of 0.001 p.p.m. of bromine and is free from interfering reactions. The values obtained for G-1 and W-1, 0.484 and 0.490 p.p.m. of bromine respectively, are lower than the average values for granites and basalts previously reported.     

石墨探针—原子吸收光谱法测定人发中痕量铟的研究

探针原子化技术是一种实现等温原子化,改善灵敏度的行之有效的方法。本文采用此方法对痕量钿进行了一系列条件试验,峰面积与钿浓度在0～50ng·ml~(-1)范围内呈线性关系,其特征量4.8pg,检出限21.5pg,相对标准偏差5.7％,并成功地测定了成人发中铟的含量,范围在12～159pg·g~(-1),回收率96.4％～103.2％。该方法灵敏度高,操作简单、快速,结果满意。     

Simultaneous determination of gallium and indium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in cationic micellar medium using derivative spectrophotometry.

A new derivative spectrophotometric method for rapid and selective trace analysis of Ga3+ and In3+ and for their simultaneous determination using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in a cationic micellar medium is reported. Molar absorptivity and Sandell's sensitivity of 1:1 Ga+ and In3+ complexes at their lambda(max) 553 nm and 558 nm are: 7.22 x 10(4) l mol(-1) cm(-1) and 5.85 x 10(4) l mol(-1) cm(-1), and 0.96 ng cm(-2) and 1.96 ng cm(-2), respectively. Linearity is observed in the concentration range 0.023-0.700 microg ml(-1) for gallium and 0.076-1.52 microg ml(-1) for indium; IUPAC detection limit is 0.012 and 0.035 ng ml(-1), respectively. These metal ions interfere with the determination of each other. However, 0.07-0.70 microg ml(-1) Ga3+ and 0.115-1.150 microg ml(-1) In3+ could be determined simultaneously when present together by the derivative method without any prior separation. The proposed procedures have been successfully applied for the individual and simultaneous determination of gallium and indium in synthetic binary mixtures, standard reference materials and environmental samples.     

Zerstörungsfreie aktivierungsanalytische Bestimmung von Mikro- und Ultramikromengen Indium in Reinstthallium und Thalliumverbindungen

Two non-destructive neutron activation methods has been described for the determination of indium in thallium metal and thallium compounds. The sensitivity of the first method based on^114mIn corresponds to 1×10^?6g (standard deviation 4,5–8%). The second method (by means of^116mIn) permits the determination of ultramicro amounts of indium up to 5×10^?11g with a standard deviation of 15%. The influence of many elements (such as Ga, Cu, Al, Cd, Zn, Pb, Ca, Mg, Bi, Fe) has been examined. The methods have been applied to the determination of indium in thallium metal, oxide, nitrate, sulphate and chloride. The data obtained agreed whith those of the spectrochemical determination.     

Amperometry with two polarisable electrodes-XI Determination of bismuth by EDTA titration

Optimum conditions have been found for a highly selective determination of bismuth via EDTA titration with biamperometric indication of the end-point. The influence of the applied potential, pH and stirring on the accuracy and selectivity of the determination has been studied. In a medium of 0.4M nitric acid only high concentrations of iron(III) and copper(II) interfere with the determination of bismuth. Zirconium, thallium(III) and indium interfere even in small concentrations. The average error of the determination of 5-100 mg of bismuth (when titrated with 0.05M EDTA solution) is +/-0-1 % rel. and for the determination of 0.5-10 mg it is +/-0.3% rel. (0.005M EDTA). The method has been verified by the analysis of a Wood's metal of known composition.     

变色酸2C分光光度法测定血清蛋白质研究

变色酸2C在pH3.82的Britton-Robinson(B-R)缓冲介质中,能与血清蛋白质形成有色复合物,λmax为560nm,比试剂本身红移约51nm,表观摩尔吸光系数为3.05×105L.mol-1.cm-1,测定蛋白质的线性范围为20~80mg.L-1。应用于人血清样品总蛋白的测定,结果与经典的考马斯亮蓝法一致,而且线性范围宽,操作与重现性都优于考马斯亮蓝法。     

Simultaneous determination of gallium(III) and indium(III) by derivative spectrophotometry

A simple, selective and sensitive derivative spectrophotometric method is proposed for the simultaneous determination of gallium(III) and indium(III) in mixtures using 1-(2-pyridylazo)-2-naphthol in cationic micellar medium, without any prior separation. Beer's law is obeyed between 2.80x10(-1)-3.63 and 4.60x10(-1)-9.20 mug ml(-1) concentration of Ga(III) and In(III) at 550 and 542 nm, the isodifferential points of indium and gallium complexes in the first-order derivative mode, respectively. The proposed method is successfully applied for the determination of gallium and indium in standard reference materials and synthetic binary mixtures with a relative error of +/-2.07 and +/-2.55%, respectively.     

Rapid Fluorometric Determination of Trace Indium(III) in Microemulsion Medium after Preconcentration and Separation by Sulphydryl Dextrane Gel

A new highly sensitive, stable, and accurate fluorometric method for the determination of indium(III) has been established in cetyltrimethylammonium bromide(CTMAB) microemulsion media. The excellent color-forming reagent 2,6,7-trihydroxy-9-(3,5-dibromo-4-hydroxyphenyl) fluorone (DBH-PF) reacts with indium(III) to form a purple complex with a 3 : 1 (ligand to metal) ratio in HAc-NaAc buffer solution at pH 4.94. The emission peak occurs at 556 nm with excitation at 525 nm. Indium(III) can be determined in the linear range of 0.005–0.30 μg mL⁻¹ with a detection limit of 0.0029 μg mL⁻¹. Foreign ions are eliminated by preconcentration and separation with sulfhydryl dextranegel (SDG). The proposed method has been satisfactorily examined for the determination of indium(III) in ore and sludge samples. The relative standard deviations are in all instances less than 3.0%, and the recoveries are between 94.7, and 99.5%. __________ From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 9, 2005, pp. 979–984. Original English Text Copyright ? 2005 by Wei Qin, Du Bin, Zhang Hui, Li Yan, Li Zaijun. The text was submitted by the authors in English.     

Determination of some catechol derivatives by a flow injection electrochemiluminescent inhibition method

A flow injection electrochemiluminescent inhibition method has been developed for the determination of some catechol derivatives based on studying the inhibition phenomena of these compounds to the electrochemiluminescence of luminol. The linear calibration range of 5x10(-8) to 1x10(-5), 5x10(-8) to 1x10(-5) and 1x10(-8) to 5x10(-5) mol l(-1(,)) the detection limit of 1.2x10(-8), 2.1x10(-8) and 5.2x10(-9) mol l(-1)were obtained for catechol, 3,4-dihydroxybenzoic acid and chlorogenic acid, respectively. The method has higher sensitivity and wider dynamic range than conventional spectrophotometric method or chemiluminescent method. The method has been successfully applied to determine chlorogenic acid in cigarettes. The mechanism of the inhibition effect was proposed. Catechol derivatives mostly react with the freshly electrogenerated oxygen species on the electrode surface and lead to the inhibition of electrochemiluminescence.     

Spectrophotometric determination of traces of gallium and indium with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol (PAN) reacts with either gallium or indium at pH 5–6 giving a red complex in an aqueous medium in the presence of N.N-dimethyl-formamide. The maximum absorption of both PAN complexes of gallium and indium in an aqueous solution is at 545 mμ. The gallium-PAN complex shows a characteristic enhancement of color by addition of small amounts of ethers. Based on this selective enhancement reaction, gallium can be determined in the presence of other metals without separation. The results of determining gallium and indium in the presence of each other are reported. Both gallium and indium form M₂(PAN)₃; but in the presence of certain organic solvents, a different gallium complex, Ga(PAN)₅, and the same indium complex, In₂(PAN)₃, are formed. The reaction of PAN with cadmium can be masked by iodide; an example of determining indium in the presence of cadmium is given. The PAN method has a sensitivity of 0.003 μg/cm² for gallium and 0.005μg/cm² for indium and an absorptivity of 24,900 for the Ga-PAN complex and of 24,500 for the In-PAN complex, respectively. The methods have been successfully applied to the determination of both gallium and indium in germanium thin films.     

Binding of warfarin influences the acid-base equilibrium of H242 in sudlow site I of human serum albumin

Sudlow Site I of human serum albumin (HSA) is located in subdomain IIA of the protein and serves as a binding cavity for a variety of ligands. In this study, the binding of warfarin (W) is examined using computational techniques and isothermal titration calorimetry (ITC). The structure of the docked warfarin anion (W-) to Site I is similar to that revealed by X-ray crystallography, with a calculated binding constant of 5.8 x 10(5) M(-1). ITC experiments (pH 7.13 and I = 0.1) carried out in three different buffers (MOPs, phosphate and Tris) reveal binding of W- is accompanied by uptake of 0.30+/-0.02 protons from the solvent. This measurement suggests that the binding of W- is stabilized by an ion-pair interaction between protonated H242 and the phenoxide group of W-.