Potentiometric determination of free acidity in presence of hydrolysable ions and a sequential determination of hydrazine

A simple potentiometric method for the determination of free acidity in presence of hydrolysable ions and sequential determination of hydrazine is developed and described. Both free acid and hydrazine are estimated from the same aliquot. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 1.2% relative standard deviation. Hydrazine content has also been determined in the same aliquot with a recovery of nitric acid is 99% with 2% relative standard deviation. The major advantage of the method is that generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal.     

Determination of tin, bismuth, antimony, indium, gallium and arsenic by solvent extraction cum atomic absorption spectrophotometry

A rapid atomic absorption spectrometric method for the determination of tin, antimony, bismuth, indium, gallium and arsenic in geological materials, steels and alloys is described. The samples are fused with sodium peroxide (for geological samples such as cassiterite and sulphides) or decomposed with sulphuric/hydrochloric acid mixture or by alkaline fusion (for silicates or bauxites) or by acid treatment (for steels, alloys and certain geological samples). The elements of interest are extracted as their iodides into methyl isobutyl ketone, stripped into aqueous solution by treatment with benzene, concentrated nitric acid and water, and determined by flame atomic-absorption spectrometry. Detailed study is made on stripping of the metals from organic phase as there no simple and rapid stripping procedures available. The method allows the determination of Sn, Sb, Bi and In down to 2 ppm and Ga down to 5 ppm. The relative standard deviations range up to 10% with an average of 2.5%. Apparent recoveries of these metals range from 90 to 110 with an average of 95% for Sb and 99% for others.     

Sequential determination of uranium (IV), free acidity and hydrazine in a single aliquot

A simple analytical procedure for the sequential determination of uranium (IV), free acidity and hydrazine in presence of hydrolysable ions is developed and described. In this method, first, uranium (IV) is determined using fiber optic aided spectrophotometry then same solution is used for determination of free acidity and hydrazine. Free acid is titrated with standard sodium carbonate solution after uranium (IV) is masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. The overall recovery of uranium (IV), nitric acid and hydrazine is 98% with 3% relative standard deviation respectively. The major advantage of the method is that it uses sodium carbonate a primary standard as titrant and generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal.     

A modified dimethylglyoxime method for the determination of nickel in sea water

A colorimetric dimethylglyoxime (DMG) method for the determination of nickel in sea water was studied in detail, and improved through close control of experimental conditions. For a maximum precipitation of 90% of the nickel a minimum period of 7 days was necessary between treatment with sodium carbonate and filtration. A salt effect resulted from: (1) a gain in absorbance due to soluble ions not precipitated by sodium carbonate, which increased with increasing salt concentration, (2) an offsetting loss in absorbance due to incomplete precipitation of nickel. The transition 3d ions precipitated by sodium carbonate exerted no discernible effect on the absorbance.A procedure is recommended by which a relative standard deviation of 0.7% was achieved. Consistent recovery yields of 97% were obtained from samples of sea water spiked with nickel collected over a period of several months.     

Estimation of metals as sulphides : Estimation of bismuth,cadmium, lead,and indium

1. It has been shown, that under proper conditions bismuth, cadmium, lead and indium can be precipitated quantitatively as pure sulphides by alkali sulphides and the precipitate weighed directly for the estimation of the motal. 2. In the case of bismuth ammonium sulphide gives a pure precipitate of Bi₂0₃ which is washed with hot water and weighed directly. 3. In the case of cadmium sodium sulphide gives a pure orange coloured precipitate of the Bulphide which is washed with water and without any further treatment, weighed as CdS. 4. In the case of lead the solution is treated with alkali sulphide, the mixture is then acidified with. acetic acid and the pure precipitate of PbS after washing with water weighed directly without heating. 5. In the case of indium treatment with ammonium sulphide gives a pure precipitate of In₂S₃ which after washing and heating can be weighed directly for the estimation of the metal. Equally good results are obtained if the mixture is acidified with acetic acid after treatment with ammonium sulphide. 6. The given procedures provide for a convenient, quick and accurate estimation of the metals.     

Extractive separation of molybdenum as Mo(V) xanthate from Iron, vanadium, Tungsten, copper, uranium and other elements

A simple and selective extraction of molybdenum is described. Tungsten is masked with tartaric acid and molybdenum(VI) is reduced in 2M hydrochloric acid by boiling with hydrazine sulphate. Iron, copper and vanadium are then masked with ascorbic acid, thiourea and potassium hydrogen fluoride respectively. The molybdenum(V) is extracted as its xanthate complex into chloroform, from 1M hydrochloric acid that is 0.4M potassium ethyl xanthate. The complex is decomposed by excess of liquid bromine, and the molybdenum is stripped into alkaline hydrogen peroxide solution. The molybdenum is then determined by standard methods. Large amounts of Cu(II), Mn(II), Fe(III), Ti(IV), Zr, Ce(IV), V(V), Nb, Cr(VI), W(VI), U(VI), Re(VII) and Os(VIII) do not interfere. Several synthetic samples and ferromolybdenum have been rapidly and satisfactorily analysed by the method.     

The application of thiosalts in analysis: A new scheme of qualitative analysis - Part C

1. Seveial modifications for improving the efficiency of the new scheme of qualitative analysis have been proposed. 2. It has been shown that 1N sodium sulphide is a more efficient and convenient reagent and may be substituted for concentrated ammonium sulphide. 3. If sodium carbonate is added along with sodium, sulphide, barium, strontium and calcium are precipitated completely with the sulphides and hydroxides and the division of these metals into two groups is prevented. 4. It has been shown that the tedious separation of cerium and thorium from the iron group by means of oxalic acid is unnecessary and these metals can be tested for conveniently with the metals of the iron group. 5. The division of thallium into the iron and copper groups can be avoided and the metal precipitated completely with the copper group by adding potassium iodide in the treatment with 1N hydrochloric acid. 6. Modified procedures liave been provided tor the detection of nickel, tellurium and gold.     

Spectrophotometric determination of pentaerythritol tetranitrate (PETN) in waste water from lead styphnate primer plants

An accurate spectrophotometric method is proposed for the determination of pentaerythritol tetranitrate (PETN) in waste water from lead styphnate primer plants by use of phenoldisulphonic acid. The waste water is filtered through a sintered glass crucible and the PETN is determined in the filtrate and the residue. In the determination of PETN in the filtrate, sodium hydroxide is added and the PETN is extracted with methylene chloride (in alkaline solution, styphnate and TNT are not extracted). The methylene chloride solution is then evaporated to dryness, the residue is treated with a solution of phenoldisulphonic acid in sulphuric acid, water and ammonia are added, and the yellow colour is measured. In the determination of PETN in the residue, the PETN is dissolved in acetone, an aliquot of the acetone solution is treated with water and sodium hydroxide, the PETN is extracted with methylene chloride and the colour is developed as above. Various factors affecting the determination were investigated. The solubility of PETN in water was studied.     

Na2EDTA反滴定法测定铜镍合金中的镍

采用Na2EDTA返滴定法测定铜镍合金中的镍含量, 用柠檬酸钠、硫代硫酸钠和酒石酸做掩蔽剂,丁二酮肟沉淀分离,以二甲酚橙为指示剂,加入过量的Na2EDTA,用氯化锌标准溶液返滴定。方法能很好地分离铜及其他杂质的干扰。试验方法用于测定铜镍合金中的镍含量,测定结果的相对标准偏差（RSD,n=9）为0.0456%～0.2409%,加标回收率为99.30%～101.10%如有残渣,过滤之后将残渣消解,用光谱测定不溶渣中的镍含量。能够满足日常样品的检测要求。     

Precipitation of metal-cupferron complexes from homogeneous solution-I: determination of copper

The cupferron complex of copper has been precipitated from homogeneous solution by the addition of phenylhydroxylamine and sodium nitrite to a cold, acidic solution containing copper(II) ions. The precipitate can be dried at 90 +/- 5 degrees and weighed without ignition to the oxide. Less than 3 mg of copper can be determined. A fairly high concentration of acetic acid is tolerable. Separation from large quantities of zinc, nickel and silver has been achieved.     

Determination of silver, antimony, bismuth, copper, cadmium and indium in ores, concentrates and related materials by atomic-absorption spectrophotometry after methyl isobutyl ketone extraction as iodides

Methods for determining ~ 0.2 mug g or more of silver and cadmium, ~ 0.5 mug g or more of copper and ~ 5 mug g or more of antimony, bismuth and indium in ores, concentrates and related materials are described. After sample decomposition and recovery of antimony and bismuth retained by lead and calcium sulphates, by co-precipitation with hydrous ferric oxide at pH 6.20 +/- 0.05, iron(III) is reduced to iron(II) with ascorbic acid, and antimony, bismuth, copper, cadmium and indium are separated from the remaining matrix elements by a single methyl isobutyl ketone extraction of their iodides from ~2M sulphuric acid-0.1M potassium iodide. The extract is washed with a sulphuric acid-potassium iodide solution of the same composition to remove residual iron and co-extracted zinc, and the extracted elements are stripped from the extract with 20% v v nitric acid-20% v v hydrogen peroxide. Alternatively, after the removal of lead sulphate by filtration, silver, copper, cadmium and indium can be extracted under the same conditions and stripped with 40% v v nitric acid-25% v v hydrochloric acid. The strip solutions are treated with sulphuric and perchloric acids and ultimately evaporated to dry ness. The individual elements are determined in a 24% v v hydrochloric acid medium containing 1000 mug of potassium per ml by atomic-absorption spectrophotometry with an air-acetylene flame. Tin, arsenic and molybdenum are not co-extracted under the conditions above. Results obtained for silver, antimony, bismuth and indium in some Canadian certified reference materials by these methods are compared with those obtained earlier by previously published methods.     

Determination of indium and thallium in indium-thallium alloys

The thallium-indium alloys were dissolved in sulphuric acid (1 + 1). In this medium thallium remained in the univalent state and could be determined directly, without a separation, by an oxidation-reduction titration with potassium bromate. The indium was determined directly with an EDTA titration. Ascorbic acid was added to maintain the thallium in the univalent state, which did not interfere. Ascorbic acid also masked any interfering tervalent thallium by effectively reducing it to the univalent state. Sharp end-points were obtained for both titrations, which were carried out in the temperature range of 50-95 degrees . The method offers excellent precision and accuracy.     

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 indium,copper and nickel in glassmaking materials and NBS standard reference materials by substoichiometric radioactivation analysis

The paper describes a method of radioactivation analysis for the determination of indium, copper and nickel. In the determination of indium, ordinary and displacement substoichiometries were applied for glassmaking materials while ordinary substoichiometry was applied for NBS standard reference materials. Copper and nickel in glassmaking materials and NBS standard reference materials were also determined by the displacement and ordinary substoichiometries. Indium contents in glassmaking materials by the two methods agreed with each other. The analytical results of indium, copper and nickel in NBS' SRM were also in good agreement with published values and certified values by NBS.     

Solvent extraction separation of cobalt(II) from nickel and other metals with cyanex 272

Cobalt(II) was quantitatively extracted at pH 8.0 with 5 x 10(-3)M Cyanex 272 [Bis(2,4,4 trimethyl pentyl) phosphoric acid] in chloroform. Cobalt(II) was stripped with 0.5M nitric acid and was determined by atomic absorption spectrometry as well as by spectrophotometry of the complex with nitroso R salt. Cobalt(II) was separated from vanadium, chromium, nickel, manganese, iron and zinc. Mixtures having different ratios of iron, cobalt and nickel were separated by proposed method.     

Dosage complexométrique de bromures et d'iodures en présence l'un de l'autre

Bromides and iodides are determined simultaneously by precipitation as silver halide In another aliquot, silver halides are oxidized, bromine being liberated, the iodate formed is then reduced to iodide which precipitates. The silver precipitates are treated with ammoniacal tetracyano nickelate and displaced nickel is determined complexometrically Bromide is determined by difference     

Solvent extraction separation of gallium with 18crown6 from chloride media

Gallium was quantitatively extracted with 0.02M 18crown6 in methylene chloride from 6M hydrochloric acid, then stripped with 1M acetic acid and determined with 2-(pyridylazo)naphthol with measurement at 545 nm. Gallium was separated from indium, thallium, lead, aluminium and bismuth. The method was applied to determination of gallium in bauxite.     

Na2EDTA返滴定法测定铜镍合金中的镍含量

采用Na₂EDTA返滴定法测定铜镍合金中的镍含量,用柠檬酸钠、硫代硫酸钠和酒石酸作掩蔽剂,丁二酮肟沉淀分离,以二甲酚橙为指示剂,加入过量的Na2EDTA,用氯化锌标准溶液返滴定,能很好地分离铜及其他杂质的干扰。方法用于测定铜镍合金中的镍含量,测定结果的相对标准偏差(RSD,n=9)为0.046%~0.24%,加标回收率为99.3%~101%。能够满足日常样品的检测要求。     

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.     

Spectrophotometric determination of boron in cobalt and nickel coatings by means of carminic acid

A method is proposed for the determination of boron in cobalt and nickel coatings deposited from borane-type baths. The deposit is dissolved in hydrochloric acid in the presence of platinum chloride as catalyst, potassium chloride and mannitol are added, and the solution is evaporated to dryness. Boron is then distilled as methyl borate into sodium hydroxide solution, the distillate is evaporated to dryness, and the boron is determined spectrophotometrically with carminic acid. The mannoitol prevents volatilization of boron during the evaporation. Evaporating the hydrochloric acid solution to dryness eliminates excess of acid and water, both of which cause incomplete recovery of boron in the distillation. The potassium, cobalt, and nickel chlorides left after the evaporation dissolve in the hot methanol during the distillation and do not interfere.