Determination of cobalt, nickel, lead, bismuth and indium in ores, soils and related materials by atomic-absorption spectrometry after separation by xanthate extraction

A method for determining approximately 0.5, mug/g or more of cobalt, nickel and lead and approximately 3 mug/g or more of bismuth and indium in ores, soils and related materials is described. After sample decomposition and dissolution of the salts in dilute hydrochloric-tartaric acid solution, iron(III) is reduced with ascorbic acid and the resultant iron(II) is complexed with ammonium fluoride. Cobalt, nickel, lead, bismuth and indium are subsequently separated from iron, aluminium, zinc and other matrix elements by a triple chloroform extraction of their xanthate complexes at pH 2.00 +/- 0.05. After the removal of chloroform by evaporation and the destruction of the xanthates with nitric and perchloric acids, the solution is evaporated to dryness and the individual elements are ultimately determined in a 20% v/v hydrochloric acid medium containing 1000 mug/ml potassium by atomic-absorption spectrometry with an air-acetylene flame. Co-extraction of arsenic and antimony is avoided by volatilizing them as the bromides during the decomposition step. Small amounts of co-extracted molybdenum, iron and copper do not interfere.     

黄钠铁矾中铁的测定

准确快速测定黄钠铁矾中铁的含量有利于控制铁湿法冶金的流程。采用氢氧化钠溶液分解试样,盐酸(1+9)溶解滤渣,蒸发除过量酸,氨水沉淀分离铜、镍、钴等元素,再用稀盐酸溶解沉淀。在盐酸介质中,SnCl_2将大部分Fe(Ⅲ)还原为Fe(Ⅱ),钨酸钠为指示剂,用TiCl_3还原呈钨蓝色,重铬酸钾滴定至蓝色褪去。再以二苯胺磺酸钠为指示剂,重铬酸钾标准溶液滴定测定样品中铁的含量。实验表明,黄钠铁矾中共存干扰元素绝大部分被分离,同时与酸溶解法进行比较,测定数据一致,相对标准偏差(n=9)小于0.1%。     

Spectrophotometric and gravimetric determination of sulfur in sebacate-base lubricants

Sulfur is determined in sebacate-base lubricants spectrophotometrically and gravimetrically. In the spectrophotometric method, a 0.2–0.3-g sample is treated with mixed acids, magnesium chloride is added, and the solution is evaporated to dryness. The sulfate is reduced to hydrogen sulfide by treatment with a mixture of hydriodic. hypophosphorous, and hydrochloric acids, and the hydrogen sulfide is distilled into ammonia solution. Lead citrate reagent is added and the brownish yellow color of lead sulfide sol is measured. An improved technique and apparatus for the distillation is described. In the gravimetric method, a 5-g sample is treated with mixed acids, antimony and tin are volatilized by treatment with hydrobromic acid, and sulfur is precipitated as barium sulfate. The recommended range of the spectrophotometric method is 0.005–0.15%,and that of the gravimetric method is 0.01–1% sulfur.     

Determination of tellurium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separations by iron collection and xanthate extraction

A method for determining approximately 0.01 mug/g or more of tellurium in ores, concentrates, rocks, soils and sediments is described. After sample decomposition and evaporation of the solution to incipient dryness, tellurium is separated from > 300 mug of copper by co-precipitation with hydrous ferric oxide from an ammoniacal medium and the precipitate is dissolved in 10M hydrochloric acid. Alternatively, for samples containing 300 mug of copper, the salts are dissolved in 10M hydrochloric acid. Tellurium in the resultant solutions is reduced to the quadrivalent state by heating and separated from iron, lead and various other elements by a single cyclohexane extraction of its xanthate complex from approximately 9.5M hydrochloric acid in the presence of thiosemicarbazide as a complexing agent for copper. After washing with 10M hydrochloric acid followed by water to remove residual iron, chloride and soluble salts, tellurium is stripped from the extract with 16M nitric acid and finally determined, in a 2% v/v nitric acid medium, by graphite-furnace atomic-absorption spectrometry at 214.3 nm in the presence of nickel as matrix modifier. Small amounts of gold and palladium, which are partly co-extracted as xanthates if the iron-collection step is omitted, do not interfere. Co-extraction of arsenic is avoided by volatilizing it as the bromide during the decomposition step. The method is directly applicable, without the co-precipitation step, to most rocks, soils and sediments.     

Liquid-liquid extraction of arsenic(III) with diluted tributyl phosphate

A 40% tributyl phosphate solution in xylene was used for the quantitative extraction of arsenic(III) from 4M hydrochloric acid/2M lithium chloride. It was stripped from the organic phase with water and determined volumetrically with potassium bromate. The period of equilibration was 3 min. Arsenic was extracted in presence of copper, cobalt, nickel, tin, bismuth, iron, cadmium and other elements which are usually associated with it in sulphide minerals and alloys.     

Determination of selenium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separation by extraction of the 4-nitro-o-phenylenediamine complex

A method for determining approximately 0.01 mug/g or more of selenium in ores, concentrates, rocks, soils, sediments and related materials is described. After sample decomposition selenium is reduced to selenium(IV) by heating in 4M hydrochloric acid and separated from the matrix elements by toluene extraction of its 5-nitropiazselenol complex from approximately 4.2M hydrochloric acid. After the extract has been washed with 2% nitric acid to remove residual iron, copper and chloride, the selenium in the extract is oxidized to selenium(VI) with 20% bromine solution in cyclohexane and stripped into water. This solution is evaporated to dryness in the presence of nickel, and selenium is ultimately determined in a 2% v/v nitric acid medium by graphite-furnace atomic-absorption spectrometry at 196.0 nm with the nickel functioning as matrix modifier. Common ions, including large amounts of iron, copper and lead, do not interfere. More than 1 mg of vanadium(V) and 0.25 mg each of platinum(IV), palladium(II), and gold(III) causes high results for selenium, and more than 1 mg of tungsten(VI) and 2 mg of molybdenum(VI) causes low results. Interference from chromium(VI) is eliminated by reducing it to chromium(III) with hydroxylamine hydrochloride before the formation of the selenium complex.     

Contributions to the basic problems of complexometry—X: Determination of nickel and cobalt in the presence of iron, copper and some other metals

A complexometric determination of nickel and cobalt in the same solution has been devised. It is based on the determination of the sum of nickel and cobalt by back-titration of added excess EDTA in a strongly alkaline medium with calcium chloride using Fluorexon (Calcein) as indicator. After oxidation of cobalt with hydrogen peroxide to form the cobalt^III- EDTA complex and screening of nickel by potassium cyanide, the liberated EDTA corresponding to the amount of nickel present is titrated with further calcium chloride. High concentrations of iron and aluminium are screened with triethanolamine. Copper and other heavy metals are screened with thioglycollic acid.     

ICP-AES法测定红土镍矿中镍、钙、钛、锰、铜、钴、铬、锌与磷的含量

建立了ICP-AES法测定红土镍矿中Ni;Ca;Ti;Mn;Cu;Co;Cr;Zn和P含量的方法。样品用HCl、HNO3溶解,加入HF和HClO4,加热至HClO4烟冒尽,用HCl溶解盐类,过滤,采用ICP-AES法同时测定滤液中Ni、Ca、Mn、Cu、Co、Zn、P;残渣经灼烧、挥硅、K2S2O7熔融、HCl浸取,所得溶液与滤液合并,测定溶液中Cr和Ti含量。方法检出限:P为0.022μg/mL,其它元素在0.0032～0.0085μg/mL之间,方法的精密度(n=7)在1.4%～2.9%之间。分析结果与分光光度法、XRF法和AAS法分析结果的相对误差:Ni、Cu、Co、Cr小于5%,Ti和Mn小于10%,Zn小于15%,Ca和P小于19%。     

Determination of radioactive and stable cobalt in marine biological materials (author's transl)]

Studies were made to develop the method for rapid determination of radioactive and stable cobalt in a single specimen of marine biological materials. The sample was dried, ashed, and dissolved in acid. The cobalt was extracted with 1-nitroso-2-naphthol benzene and determined by absorptiometry on the benzene phase. Then, the organic solution was evaporated to dryness, and the residue was treated with nitric-perchloric acid mixture to decompose any organic matter, and taken up with hydrochloric acid. The cobolt was extracted from the solution with TIO A-toluene, and the radioactive cobalt was determined by liquid scintillation counting on the toluene phase. Examinations were made on the chemical yield and on the decontamination factor of the fission product nuclides. Analysis were made on the marine biological samples of Urazoko Bay, Fukui prefecture. Agreement of the radioactive cobalt data between that by the present method and that by Ge(Li) gamma ray spectometry was good. Also, the stable cobalt value by the present method agreed well with that by neutron activation analysis method.     

Semimicro spectrophotometric determination of nitroglycerine in propellants by use of 2,4-xylenol

A semimicro spectrophotometric method using 2,4-xylenol is proposed for the determination of nitroglycerine in propellants. The propellant is extracted with methylene chloride, the extract is diluted, and a 10-ml aliquot is evaporated just to dryness. Then 2,4-xylenol reagent and 63% v/v sulphuric acid are added to hydrolyse the nitroglycerine to nitrate and form 6-nitro-2,4-xylenol which is steam-distilled in a Parnas-Wagner Kjeldahl distillation apparatus into a water-ammonia-isopropyl alcohol mixture. The absorbance of the yellow solution of the anion of the 6-nitro-2,4-xylenol is measured. The calibration curve is prepared from potassium nitrate and an empirical factor (5.50) is used to convert from nitrogen content to nitroglycerine (the theoretical factor is 5.40). The 2,4-xylenol should be added before the sulphuric acid in order to prevent interference from diphenylamine and ethyl centralite. The method is designed for the usual nitrocellulose double-base propellants containing 8-50% of nitroglycerine.     

An atomic absorption spectrophotometric method for the determination of trace amounts of zinc in canned juices after ion exchange separation

An atomic absorption spectrophotometric method is described for the determination of microgram quantities of zinc in canned juices. After sample digestion in concentrated nitric acid, the solution is evaporated till near dryness, and then a solution of 2 M HCl is added to form tetrachlorozincate (II) ion. This acid solution, containing the zinc complex is passed through an ion-exchange column (anion exchange resin, chloride form, which is preconditioned by passing 1 M HCl solution). Zinc is eluted from the column with 0.01 M HCl solution. After evaporation to dryness, the residue is dissolved in 1% (v/v) HNO3, and then atomized into an air-acetylene flame. The limit of detection of the method is 0.15 micrograms ml-1 Zn. The analytical aspects of the proposed method, including the standard addition technique are discussed.     

Determination of bismuth in ores, concentrates and non-ferrous alloys by atomic-absorption spectrophotometry after separation by diethyldithiocarbamate extraction or iron collection

Two simple, reliable and moderately rapid atomic-absorption methods for determining trace and minor amounts of bismuth in copper, nickel, molybdenum, lead and zinc concentrates and ores, and in non-ferrous alloys, are described. These methods involve the separation of bismuth from matrix elements either by chloroform extraction of its diethyldithiocarbamate (DDTC) complex, at pH 11.5–12.0, from a sodium hydroxide medium containing citric acid, tartaric acid, EDTA and potassium cyanide as complexing agents, or by co-precipitation with hydrous ferric oxide from an ammoniacal medium. Bismuth is ultimately determined, at 223.1 nm after evaporation of the extract to dryness in the presence of nitric and petchloric acids and dissolution of the salts in 20% v/v hydrochloric acid, or by dissolution of the hydrous oxide precipitate with the same acid solution, respectively. Results obtained by both methods are compared with those obtained spectrophotometrically by the iodide method after the separation of bismuth by DDTC and xanthate extractions.     

Spectrophotometric determination of boron in complex matrices by isothermal distillation of borate ester into curcumin

In situ distillation of borate ester into the curcumin solution has been developed for the spectrophotometric determination of boron in a variety of complex matrixes. A polypropylene vessel containing the sample solution was placed inside a vessel (PP) containing 10 ml of curcumin solution and the distillation was carried out at room temperature/on a water bath. The borate ester collected in to the curcumin solution was evaporated to dryness on the water bath, taken in acetone and the absorbance was measured at 550 nm. In situ distillation of borate ester directly into the chromogenic reagent eliminates tedious sample treatment (before and/or after borate separation), use of methanol, complicated quartz set up, possible loss of boron and reduces the analysis time significantly. In situ dehydration of sample solution by ethanolic vapour in the absence of dehydrating acid prevents the formation of fluoborate and co-distillation of potential anionic interferents (nitrate and fluoride). This developed method has been applied for the determination of traces of boric acid in boron powder by the distillation of methyl borate at room temperature. For other matrixes (water, uranium oxide, uranyl nitrate, fluoride salt, etc.) distillation of ethyl borate was carried out on the water bath. LOD (3σ) was 5 ng g⁻¹ for water and 30 ng g⁻¹ for solid samples.     

Spectrophotometric determination of calcium in zirconium powder by use of murexide

An accurate spectrophotometric method is proposed for the determination of calcium in zirconium powder by use of murexide. A 0.4-g sample is dissolved in hydrofluoric and sulphuric acids, the solution evaporated to fumes of sulphuric acid, and a mercury cathode electrolysis made if more than 0.05% copper or nickel is present. Ammoniacal precipitation in the presence of ammonium chloride separates zirconium and other elements and an aliquot of filtrate is collected, equivalent to 0.2 g of sample. The ammonium salts are destroyed with nitric and hydrochloric acids and the calcium is determined with murexide. The high reagent blank is shown to be due to the reagent grade nitric acid, hydrochloric acid, and ammonium hydroxide.     

Rapid technique for distillation of methyl borate for ICP atomic-emission spectrometric determination of boron in steel

The analysis time for determination of boron in steel can be remarkably shortened by simultaneous distillation of methyl borate and evaporation of the distillate for analysis by ICP atomic-emission spectrometry. Methyl borate, distilled with a large quantity of methanol, is collected in 4% sodium hydroxide solution heated in a water-bath at 90 degrees. As the boiling point of the mixture of absorption solution and methanol is lower than 90 degrees, the solvent mixture is easily evaporated. The limit of detection corresponds to 35 ng of boron in 0.5 g of steel.     

The determination of microgram and sub-microgram amounts of boron : II. The separation of boron by distillation and the evaporation of distillates

Methyl alcohol distillates containing μg amounts of boron may be evaporated without loss of boron by first adding water, sodium hydroxide and glycerol. The resulting residues can be used directly in the curcumin absorptiometric methods previously described. The distillation techniques developed over the last decade by the United Kingdom Atomic Energy authority are briefly described, as these can be used for the separation of boron from practically all types of sample, including organic matter after it has been ashed with lime. In all cases aqueous solutions of the samples are made slightly acid (pH 1.5–5) and evaporated nearly to dryness Residues are then treated with methyl alcohol in one of three ways according to their properties. It is essential to use all-silica distillation apparatus and platinum dishes for collecting distillates. Notes are given of other precautions necessary to minimize contamination from reagents and other sources. The methods are rapid and suitable for routine analysis on up to 10 g of sample. Under favourable conditions, the limit of detection is of the order of 0.01 p.p.m. of boron. A precision of better than 5% can be obtained with amounts exceeding about 0.2 p.p m.     

An improved technique for the spectrophotometric determination of nitrate with 2,4-xylenol

An improved method is proposed for the spectrophotometric determination of nitrate with 2,4-xylenol. The sample in aqueous (1.7 + 1 ) sulfuric acid is treated with 2,4-xylenol to produce 6-nitro-2,4-xylenol which is distilled into an ammoniacal water—isopropanol mixture. The intense yellow color of the ammonium salt of 6-nitro-2,4-xylenol is measured at 455 nm. The distillation is done in a Parnas—Wagner Kjeldahl Semimicro distillation apparatus. The isopropanol keeps the excess of 2,4-xylenol in solution. Two procedures are described. In the first (applicable to samples containing alkali nitrates but no chloride, alkaline earth, or ammonium salts), the solution is evaporated to dryness, and (1.7 + 1) sulfuric acid and 2,4-xylenol in acetone are added. In the second (applicable to samples containing chloride, alkaline earth, or ammonium salts), concentrated sulfuric acid is added dropwise to a cooled aliquot and the 2,4-xylenol reagent is then added; if chloride is present, it must be removed by prior precipitation with silver sulfate. Nitrite shows a slight interference which depends on the amount of nitrate and nitrite present.     

A rapid geochemical spectrophotometric determination of tungsten with dithiol

1-g sample is decomposed with nitric and hydrofluoric acids, and after evaporation of the solution to dryness the residue is dissolved in concentrated hydrochloric acid. A clear aliquot is treated with stannous chloride to inhibit interferences. The blue tungsten dithiol complex is developed at a temperature of 85 degrees over a half-hour period. The complex is extracted into 2 ml of heptane and the tungsten is determined spectrophotometrically with a sensitivity of 0.5 ppm. Fifty samples per man-day can be analysed in this manner.     

Determination of boron in high-purity silica using direct current plasma emission spectrometry

The method involves decomposition with hydrofluoric acid-nitric acid in the presence of mannitol in a simple closed Teflon PFA vessel and subsequent evaporation of silica without detectable losses of boron. The boron is determined by direct current plasma emission spectrometry. The detection limit is 0.76μg g^?1. The possible losses of boron resulting from evaporation of the solution to dryness were investigated.     

Application of the fission-track technique to the determination of uranium in natural waters

A procedure for the determination of the uranium content of natural waters is presented. To 100 ml of natural waters, 200 ml of conc. hydrochloric acid are added and this solution is passed through a 6-ml column of Dowex 1-X8. The uranium is eluted with 60 ml of 0.1M hydrochloric acid, and the eluate is evaporated to dryness. The residue is subjected to the fission-track technique described previously. The uranium content of the river waters in Fukuoka City was determined.