The determination of trace amounts of zirconium,hafnium, thorium and cerium in silicate rocks

A method is described for the determination of traces of zirconium, hafnium, cerium and thorium in rocks. After the sample has been opened up, these elements are separated from the major component elements by extraction from 10 N nitric acid with a 40% solution of tri-n-butyl phosphate, cerium being oxidised with bro-mate. After back-extraction the elements are separated from each other and from other extracted elements by cation exchange. Zirconium is determined photometrically with quinalizarin sulphonic acid which gives about twice the sensitivity of alizarin red S. Thorium is determined photometrically with thorin, and cerium by utilizing its bleaching action on iron(II) phenanthroline. Hf is determined spectro-graphically.     

Determination of trace amounts of zirconium in silicates by cation-exchange chromatography and spectrophotometry with xylenol orange

An ion-exchange scheme and colorimetric determination with Xylenol Orange are used for estimating traces of zirconium in silicate rocks.     

Determination of trace amounts of barium in silicate rocks and minerals by ion-exchange Chromatography and atomic-absorption spectrophotometry

Trace amounts of barium are determined in the standard silicate rocks and minerals, W-1, AGV-1, BCR-1, DTS-1, GSP-1, G-2 of the U.S. Geological Survey and BR, GA, GH, GR, UB-N, DR-N, BX-N, DT-N, VS-N, FK-N, GS-N of the Centre de Recherche Petrographique et Geochimique de Nancy and the Association Nationale de la Recherche Technique. After an ion-exchange separation, the analyses are carried out by atomic-absorption spectrophotometry. The separation is performed to eliminate interferences due to matrix effects.     

Spectrofluorimetric determination of trace amounts of thorium

A spectrofluorimetric method, based on the formation of a fluorescent complex with salicyladehyde carbohydrazone, is optimized for the determination of thorium (20–800 μg l^?1) at “pH” 1.3–1.7. The relative standard deviation is 2.7% for 100 μg Th l^?1. The method is applied to synthetic mixtures containing various amounts of thorium and to the determination of thorium in monazite samples.     

Polarographic determination of trace amounts of thorium

A sensitive linear-sweep polarographic method for the determination of thorium is described. It is based on the thorium complex with Xylidyl Blue I (XBI) in a medium containing ethylenediamine, 1,10-phenanthroline, oxalic acid and ninhydrin, at pH 10.5-11.5. The complex has been proved to be Th(XBI)(2), with log beta' = 9.6. The method can be used to determine trace amounts of thorium over the range 3.5 x 10(-8)-3 x 10(-6)M. The detection limit is 1 x 10(-8)M. A solvent extraction procedure is necessary to eliminate interference from several cations. The method has been applied to determination of traces of thorium in minerals, with good results.     

Rapid determination of nanogram amounts of tellurium in silicate rocks

A hydride-generation flameless atomic-absorption technique is used to determine as little as 5 ng g^-1 tellurium in 0.25 g of silicate rock. After acid decomposition of the sample, tellurium hydride is generated with sodium borohydride and the vapor passed directly to a resistance-heated quartz cell mounted in an atomic-absorption spectrophotometer. Analyses of 11 U.S. Geological Survey standard rocks are presented.     

Spectrophotometric determination of trace amounts of beryllium in silicate materials

Although photometric determination of beryllium is generally quite satisfactory in trace analysis, application to geochemical samples is restricted because of the numerous interfering ions. Introduction of an extraction procedure eliminates the interference of Al and Fe, which occur in high concentrations in most silicate rocks, and enables beryllium to be determined with Eriochrome Cyanine R. Use of the method for analysis of six international geochemical reference samples containing between 1 and 30 ppm beryllium has given satisfactory results (relative standard deviation from 1.6 to 7.8%).     

Updated determination of trace amounts of zinc with dibromo-O-nitrophenylflurone by primary-secondary wavelength spectrophotometry

The reaction between zinc (Zn²⁺) and dibromo-o-nitrophenylflurone (DBNPF) was studied at pH 9. It was sensitive and selective in the presence of fluoride and triethanolamine. Due to the effect of excess DBNPF, the new method named as primary-secondary wavelength spectrophotometry (PSWS) was applied instead of ordinary spectrophotometry for the determination of trace amounts of zinc. Results showed that such a method resulted in a better precision and higher accuracy than the ordinary method. By analyzing several samples, the relative standard deviations were less than 7.8% and the recovery rate of Zn between 93.3 and 110%. This article was submitted by the authors in English.     

Simultaneous determination of iron and titanium in silicate rocks by using diantipyrinylmethane with dual-wavelength spectrophotometry

The simultaneous determination of iron(III) and titanium(IV) with diantipyrinylmethane (DAPM) based on dual-wavelength spectrophotometry is described. The absorbances at 388 nm, 470, and 514.9 (A₃₈₈, A₄₇₀, A_514.9, respectively) are measured and a ratio k (= A₃₈₈/A_514.9) of 3.64 is introduced to allow simultaneous determinations of iron and titanium. The apparent molar absorptivities obtained by using the differences in absorbance, A₃₈₈—A_514.9, for titanium and A₄₇₀ × k — A₃₈₈ for iron, are 1.41 × 10⁴ and 1.13 × 10⁴ 1 mol^?1 cm^?1, respectively. The calibration graphs are linear up to 20 mg 1^?1 iron(III) oxide and 5 mg 1^?1 titanium(IV) oxide. The proposed method was applied successfully to the determination of iron and titanium in silicate rocks. The protonation equilibria of DAPM were also studied; K_a1 and K_a2 are estimated as 10^1.10 and 10^0.75, respectively.     

Rapid determination of thorium in ores : Estimation of trace amounts of thorium in complex minerals and ores

A very rapid method for the estimation, of trace amounts of thorium up to 0.01 per cent. or thereabouts even in complex minerals like ilmenite and columbitetantalite has been described. Thorium is collected in an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposition of the mineral with sodium peroxide. Thorium is next collected as fluoride with lanthanum as a carrier, precipitated as thorium iodate in potassium iodate-oxalic acid mixture and finally titrated against 0.01N sodium thiosulphate. Accurate results are obtained within a short time of two working days.     

The determination of trace amounts of chlorophenols by high-performance liquid chromatography

A method is given for the separation and determination of eight chlorophenols using HPLC. The chlorophenols after extraction from aqueous solution by means of diethyl ether are taken up in a 1% methanol-petroleum spirit mixture and injected onto the column. Separation of a mixture of all eight chlorophenols can be achieved in 25 min and a linear relationship exists for each chlorophenol for concentrations in the range 0.1–1.0 ppm.     

Determination of trace amounts of thorium by electroanalytical techniques

Trace amounts of thorium have been determined in the presence of uranyl nitrate and ammonium diuranate (as interferents) by cyclic voltammetry, differential-pulse polarography, differential-pulse voltammetry, square-wave voltammetry and anodic-stripping voltammetry. The determination is based on the substitution of thorium for copper, lead and cadmium in their EDTA complexes and voltammetric measurement of the displaced metal ion. The detection limits ranged between 2 x 10(-7) and 1 x 10(-6)M (r.s.d. 2-7%) for solutions free from the uranium compounds, and between 8 x 10(-7) and 5 x 10(-6)M (r.s.d. 3-5%) in the presence of the uranium compounds at concentrations up to about 1000 times that of thorium. The detection limits depend on both the particular technique and the EDTA complex employed. Anodic-stripping voltammetry gave detection limits of 8 x 10(-8) and 10(-7)M in the absence and presence of uranium respectively.     

溴取代紫外光度法同时测定痕量磺胺嘧啶和磺胺二甲嘧啶

提出了同时测定痕量磺胺嘧啶(SD)和磺胺二甲嘧啶(SM2)的溴取代紫外光度分析法, 实验结果表明: 在6×10-5 mol/L Br2, 2.5×10-3 mol/L KI溶液和体积分数40%乙醇溶液中, 测定SD和SM2的线性范围分别为: 0～2.25 mg/L, 和0～1.125 mg/L, 摩尔吸光系数(L·moL-1·cm-1)分别为: 在水中9.66×104和8.16×104, 在乙醇水溶液中1.25×105, 1.99×105. 用此法对猪肉中SD和SM2进行测定, 猪肉中SD和SM2的质量分数分别为7.53、7.35 mg/kg, 回收率在91.4%～104.4%, SD和SM2的相对标准偏差分别为0.5%、1.5%.     

Determination of trace amounts of manganese in nickel by fourth-derivative spectrophotometry

Fourth-derivative absorption spectra were used to determine trace amounts of manganese in nickel salts. Optimum conditions for the oxidation of microgram amounts of Mn(II) to MnO(-)(4) in the presence of large amounts of nickel were established. Fourth-derivative spectra provided good sensitivity and selectivity for this determination. Attention has been paid to the effect of instrumental parameters on the results obtained. Limitations of the peak-to-trough and zero-crossing measurement techniques have been examined. Manganese (1 x 10(-3)-2 x 10(-5)%) in nickel salts (nitrate, sulphate and chloride) and in nickel powder was determined with good precision and accuracy.     

阻抑动力学分光光度法测定痕量碘

研究了在稀H3PO4介质中,痕量碘离子对NO-2催化溴酸钾氧化吖啶橙的阻抑作用,建立了测定痕量碘离子的阻抑动力学光度分析的新方法。测定碘离子的线性范围为0～0.40μg/mL,检出限为7.3×10-9g/mL。已用于食品中的微量碘的测定。     

Highly accurate determination of trace amounts of uranium in standard reference materials by spectrophotometry with chlorophosphonazo III after complete separation by anion and cation exchange chromatography

Summary A method is described for the highly accurate determination of trace amounts of uranium in standard reference materials. The uranium is separated from the bulk elements by anion-exchange chromatography, eluting most elements with 6 M hydrochloric acid and iron(III) with 0.5 M hydrochloric acid in 90% acetone. After elution of uranium with 0.1 M hydrochloric acid, residual traces of other elements are separated by a very selective cation-exchange procedure using a 3 g resin column. Finally the uranium is determined in the hexavalent state by spectrophotometry at 672 nm of its complex with chlorophosphonazo III at pH 1.1±0.2 in the presence of DTPA. Results are very accurate and precise even on a semi-routine basis. Relevant elution curves and results are presented for recovery tests and for the analysis of the 10 South African UREM standard materials.

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Methode hoher Genauigkeit zur spektalphotometrischen Bestimmung von Uranspuren in Standard-Referenzmaterialien mit Chlorphosphonazo III nach Abtrennung durch Anionen- und Kationen-Austausch-Chromatographie

Zusammenfassung Das Uran wird von den Hauptelementen durch Anionenaustausch abgetrennt, wobei die meisten Elemente mit GM HCl und Eisen(III) mit 0,5 M HCl in 90 %igem Aceton eluiert werden. Nach der Elution von Uran mit 0,1 M HCl werden die restlichen Spuren anderer Elemente durch ein selektives Kationenaustauschverfahren (3 g Harz) abgetrennt. Das Uran wird schließlich in der sechswertigen Form als Chlorphosphonazo-III-Komplex in Gegenwart von DTPA bei 672 nm (pH 1,1±0,2) spektralphotometrisch bestimmt. Selbst bei halbroutinemäßiger Ausführung werden sehr genaue Resultate erhalten (Wiederfindung 99,7–100%). Analysenergebnisse für 10 Südafrikanische Standardmaterialien werden angegeben.

Dedicated to Prof. Dr. E. Blasius on occasion of his 60th birthday     

Determination of trace amounts of cobalt by solvent extraction--second derivative spectrophotometry

A sensitive derivative spectrophotometric method is described for the determination of microamounts of cobalt based on the integration of liquid-liquid separation and reaction, in dichloroethane, of the analyte with 3-(4-phenyl-2-pyridinyl)-5-phenyl-1,2,4-triazine (PPT) and 2,4,6-trinitro-phenol (picric acid). Cobalt was thus determined in the range 7.2-500 ng/ml. The method has a high selectivity with a detection limit of 2.2 ng/ml. The relative standard deviations were 3.2 and 1.5% for 20 and 100 ng/ml cobalt, respectively. The proposed method was applied to the determination of the analyte in vitamins.