Determination of antimony in rocks and sulphide ores by flame and electrothermal atomic-absorption spectrometry

Atomic-absorption methods for determination of antimony at mug/g levels in rocks and sulphide ores by flame atomization (FAA) and electrothermal atomization (ETAA) have been described. The FAA method involves the separation of antimony from matrix elements by extraction as the iodide into methyl isobutyl ketone containing tri-n-octylphosphine oxide, from dilute hydrochloric acid solution, followed by direct aspiration of the extract into an air-acetylene flame. If necessary, antimony is first separated from copper and lead by co-precipitation with hydrous ferric oxide from ammoniacal medium and by precipitation of lead as lead sulphate. The ETAA method involves co-precipitation of antimony with hydrous ferric oxide followed by dissolution of the precipitate in dilute nitric acid, mixing with nickel solution as releasing agent, and ETAA measurement by use of a tungsten strip atomizer.     

Synthesis of 2,6-diaryl-substituted pyrylium and 4-alkox yc hromylium salts with various anions

A method is proposed for the synthesis of 2,6-diphenyl-substituted pyrylium salts and 7-hydroxy-4-ethoxychromylium salts with various anions on the basis of the condensation of ethyl orthoformate with aliphatic-aromatic ketones in the presence of acid catalysts (hydrogen chloride, hydrogen bromide, hydrogen iodide, and 92% sulfuric acid) and Lewis acids (aluminum chloride, ferric chloride, and stannic chloride).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 160–163, February, 1971.     

Determination of simple and complex iodides with ferric chloride-an alternative to the andrews titration

The iodide content of simple and complex iodides can be extracted as iodine after dissolution of the sample with acidified ferric chloride solution. Most iodides can thus be decomposed in 3M hydrochloric acid medium. A suitable extraction flask is described. Information on the cation oxidation state can be obtained by titrating the released ferrous ions in situ. A precision of 0.2% for 1-5 mmoles of iodide is attainable.     

Isolation and spectral characteristics of Ferric Iodide

Ferric iodide is isolated pure for the first time as a dark purple solid when a hexane solution of diiodotetracarbonyliron(II) and diiodine is exposed to actinic radiation. Its identity is confirmed by elemental analysis and quantitative conversion to the known tetraiodoferrate(III) by treatment with tetra-n-butylammonium iodide. Although persistent in the solid state, ferric iodide is readily decomposed in solution to ferrous iodide and 0.5 mol diiodine quantitatively.     

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.     

Determination of antimony in concentrates, ores and non-ferrous materials by atomic-absorption spectrophotometry after iron-lanthanum collection, or by the iodide method after further xanthate extraction

Methods for determining trace and moderate amounts of antimony in copper, nickel, molybdenum, lead and zinc concentrates and in ores are described. Following sample decomposition, antimony is oxidized to antimony(V) with aqua regia, then reduced to antimony(III) with sodium metabisulphite in 6M hydrochloric acid medium and separated from most of the matrix elements by co-precipitation with hydrous ferric and lanthanum oxides. Antimony (>/= 100 mug/g) can subsequently be determined by atomic-absorption spectrophotometry, at 217.6 nm after dissolution of the precipitate in 3M hydrochloric acid. Alternatively, for the determination of antimony at levels of 1 mug/g or more, the precipitate is dissolved in 5M hydrochloric acid containing stannous chloride as a reluctant for iron(III) and thiourea as a complexing agent for copper. Then tin is complexed with hydrofluoric acid, and antimony is separated from iron, tin, lead and other co-precipitated elements, including lanthanum, by chloroform extraction of its xanthate. It is then determined spectrophotometrically, at 331 or 425 nm as the iodide. Interference from co-extracted bismuth is eliminated by washing the extract with hydrochloric acid of the same acid concentration as the medium used for extraction. Interference from co-extracted molybdenum, which causes high results at 331 nm, is avoided by measuring the absorbance at 425 nm. The proposed methods are also applicable to high-purity copper metal and copper- and lead-base alloys. In the spectrophotometric iodide method, the importance of the preliminary oxidation of all of the antimony to antimony(V), to avoid the formation of an unreactive species, is shown.     

测定尿中痕量碘的高锰酸钾-亚砷酸体系催化光度法

在硫酸和磷酸的介质中,碘离子催化高猛酸钾与亚砷酸反应生成的锰（Ⅲ）氧化砷酸的反应,据此建立了催化光度法测定痕量碘的新方法。该法的检出限为0．4μg/L,测定的线性范围为1．0－25．0μg/L。应用该法测定了尿样中痕量碘的含量,获得了满意的结果,测定样品的相对标准偏差（n＝6）为2．5％－3．7％,加标回收率为96．4％－102．6％。     

A convenient iodination method for alcohols using cesium iodide/methanesulfonic acid and its comparison using cesium iodide/p-toluenesulfonic acid or cesium iodide/aluminium chloride

In situ generation of hydrogen iodide from cesium iodide/methanesulfonic acid was found to be an attractive reagent combination for the conversion of alkyl, allyl, and benzyl alcohols to their corresponding iodides under mild conditions. The method is compared with that using cesium iodide/p-toluenesulfonic acid or cesium iodide/aluminium chloride.     

The determination of tin in rocks by thermal neutron activation

A fast routine method for the determination of tin in rocks is discussed. The method is based on coprecipitation of tetravalent tin with ferric hydroxide, followed by a short irradiation in a high thermal neutron flux, extraction in toluene from 1∶1 sulphuric acid which is 5N in potassium iodide, and counting of^123mSn (T=40 m) or^125mSn (T=9.7 m) with a well-type NaI detector. In the present work^125mSn was used. The lower limit of determination is governed by the blank of the reagents. For a sample of at least one gram it is ≌ 0.2 μg Sn·g⁻¹.