Oxidation of hydroxylamine by ferricyanide in presence of zinc sulfate: A rapid method for estimating hydroxylamine and hydrazine in a mixture

The direct titration of alkaline ferricyanide in presence of zinc sulfate with hydroxylamine sulfate has been studied. A clear white precipitate of zinc potassium ferrocyanide indicates the end-point. Hydroxylamine is oxidized to nitric acid and water, and millingram-quaantities of hydroxylamine; can be determinred. In the absence of zinc sulfate and in weakly alkaline medium, hydrazine and hydroxylamine are converted to nitrogen, while in presence of zine sulfate hydrazine is oxidized to nitrogen By ferricyanide oxidation of a mixed sample uinler different conditions, hydrarine and hydroxylamine when present together can be determined rapidly.     

Oxidative determination of thiosulphate by alkaline ferricyanide using osmium tetroxide as a catalyst

Summary The catalytic action of osmium tetroxide has been utilised in the determination of thiosulphate by oxidation to sulphate with alkaline ferricyanide. Both direct and indirect procedures were developed. In the former the titration was carried out either ways using amperometric detection. In the latter, both the excess ferricyanide and ferrocyanide formed, were determined by arsenious oxide or iodometrically with thiosulphate, and by ceric sulphate respectively. The high conversion factor, availability of alternate procedures, use of potassium ferricyanide as a standard oxidant with a high molecular weight are characteristic features of this redox procedure.     

Oxidations and reductions of iron-cyanogen compounds of cobalt,nickel, cadmium and zinc

I. Cobalt ferrocyanide is oxidized by bromine water, by nitrous acid or by hydrogen peroxide in presence of acids to cobalt ferroferricyanide (cobalt Prussian blue), while cobalt ferricyanide is reduced by sulfurous acid to cobalt Prussian blue.II. Nickel ferrocyanide is oxidized by nitrous acid or by hydrogen peroxide in presence of acids to nickel ferricyanide.III. Nickel ferrocyanide and cadmium ferrocyanide are oxidized by bromine water to the ferricyanides.IV. The ferricyanides of nickel, cadmium and zinc are reduced by sulfurous acid to the ferrocyanides.     

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.     

High frequency t1tration and estimation of ions: Determination of barium,lead, thallium,calcium, cerium,copper and silver

Solutions of potassium chromate, ammonium oxalate and ferrocyanide are used as titrants for the high frequency titration of metal ions. Lead and barium, up to 20 mg, and thallium, up to 50 mg, are estimated with chromate und yield good results. Similarly, ammonium oxalate behaves satisfactorily when the concentration of calcium is not more than 10 mg and that of cerium is between 10 and 40 mg. Copper and silver can be titrated by ferrocyanide only up to a concentration of 10 and 20 mg, respectively. In all cases, the pH of the solution should preferably be between 6.0 and 6.5, though it can be extended in some cases to as low as 5.0.     

A computer controlled continuous dilution dilatometer for the determination of solute molar volumes and direct measurement of reaction volumes in solution

The design and operation of a computer controlled continuous dilution dilatometer utilizing a diode array detection system is presented. To test the accuracy and reproducibility of the technique, apparent molar volumes of dilute aqueous solutions of potassium ferricyanide and potassium ferrocyanide have been measured. To provide supporting data for high pressure studies of reaction volumes and molar volume change in solutions of high ionic strength, study of these electrolytes was extended by dilution into 0.1M and 1.0M potassium nitrate solutions rather than extrapolation to zero ionic strength as is normal. In addition, the system has been used to determine reaction volumes of some acid-base reactions by direct measurement, using the equipment as an automatic titration dilatometer.     

The reduction of ferricyanides and a sensitive test for the detection of hydrogen peroxide

Yellow zinc ferricyanide is reduced by heating to white zinc ferrocyanide by hydrogen peroxide in the presence of zinc sulphate and sodium, acetate. Copper ferricyanide, however, is reduced to brown copper ferrocyanide at room temperature, by means of hydrogen peroxide in the presence of copper sulphate and sodium acetate. The latter reaction can be applied for the detection of extremely small quantities of hydrogen peroxide both in a test tube (2.5 γ in 1 ml) and as a spot test (0.5 to 1 γ).     

Formation of ferricyanides-I silver(I), copper(II) and cadmium(II)

With potassium ferricyanide copper(II) forms KCu(10),[Fe(CN)(6)](7) quantitatively in 0.5M potassium nitrate medium. Cadmium forms Cd(3)[Fe(CN)(6)](2) if the ferricyanide is added to the cadmium solution in absence of extra potassium, and KCd(10)[Fe(CN)(6)](7) if potassium is added first, or if the cadmium solution is added to the ferricyanide. Silver forms Ag(3)Fe(CN)(6) only.     

Determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys by atomic-absorption spectrophotometry

A simple atomic-absorption spectrophotometry method is described for the determination of silver, bismuth, cadmium, copper, iron, nickel and zinc in lead- and tin-base solders and white-metal bearing alloys, with use of a single sample solution. The sample is dissolved in a mixture of hydrobromic acid and bromine, then fumed with sulphuric acid. The lead sulphate is dissolved in concentrated hydrochloric acid. The method is particularly suitable for the determination of silver and bismuth, which are co-precipitated with lead sulphate. The other elements can also be determined after removal of the lead sulphate by filtration.     

Oxidation of selenite by alkaline ferricyanide using osmium tetroxide as a catalyst

Summary Oxidation of selenite to selenate by alkaline ferricyanide catalysed by osmium tetroxide was followed by direct and indirect procedures. Either the ferrocyanide was titrated with selenite solution at 8–10% overall alkalinity or vice versa using amperometric or potentiometric end point. In the indirect procedure the excess ferricyanide was determined by amperometric titration with arsenious oxide at 10–15% alkalinity, and the ferrocyanide with ceric sulphate using o-phenanthroline or amperometric indicator. A cerimetric determination of ferricyanide based on this reaction is described.Sincere thanks of the authors are due to Dr. S. S. Joshi, D. Sc. (London), for kind interest in the work.     

Reaction of thiocyanates with ironcyanogen compounds of silver

Silver fenocyanide as well as Silver ferricyanide are converted into silver thiocyanate by treating with thiocyanate ions, while feirocyanide ions or ferricyanide ions are formed at the same time. Silver ferrocyanide as well as silver ferricyanide are dissolved by solutions of thiocynates of higher concentrations.     

A rapid iodometric method for the determination of copper and zinc

A method has been described for the iodometric simultaneous determination of zinc and copper. Copper is determined in the presence of sufficient KCNS and a small amount of KI. This is followed by the titration of the iodine equivalent to the zinc, which is liberated by the addition of potassium ferricyanide solution.Interference is eliminated completely by keeping the solution neutral or just acid with phosphoric acid.Within the range under investgation, results are obtained which are accurate to ± 0.7%.     

Chelatometrische bestimmung von zink-, cadmium- und bleiionen in anwesenheit von variaminblau als redoxindikator

A direct chelatometric method for the determination of zinc, cadmium and lead ions was developed. Using the redox systems potassium ferrocyanide-potassium ferricyanide and Variamine Blue as redox indicator, the determination could be carried out at pH 5 with sufficient accuracy Magnesium, barium, strontium and calcium do not disturb the determination. In solutions containing zinc, lead or cadmium ions, magnesium can also be determined when Eriochrome Black T is used as the indicator.     

Iodine trichloride as an analytical reagent for determination of some organic compounds

Procedures are described for the determination of organic compounds with iodine trichloride under Andrews's titration conditions. Samples are directly titrated with iodine trichloride or first reacted with an excess of iodine monochloride, with subsequent titration of the iodine formed. The direct titration is done initially in feebly acid medium, then the acidity is raised (biotin, methionine, cystine and thiomersal). Pre-oxidation with iodine monochloride is used if the organic compound reacts slowly [tryptophan and arsenic(III) compounds] or is determined in bicarbonate medium (hydroxylamine and thiosemicarbazide). The ferrocyanide formed by the reduction of ferricyanide (by thiourea and allylthiourea) can also be titrated. Arsenic(V) compounds are determined after reduction to arsenic(III), and iodine in organic compounds is converted into iodide by alkaline fusion into iodide and the iodide titrated.     

Thymolphthalin as an Analytical Reagent: 1. Spectrophotometric Determination of Ferricyanide and Ferrocyanide

Thymolphthalein (I) as an acid-base indicator is successfully reduced in sodium hydroxide medium and zinc dust into a colorless reagent (Thymolphthalin (III)). The latter is used as an analytical reagent in the colorimetric determination of some mildly strong oxidising agents such as potassium ferricyanide. Ferricyanide, ferrocyanide and a mixture of both are spectrophotometrically determined at 592 nm. Dichromate oxidises ferrocyanide to ferricyanide without interference on the reaction. The results obtained showed that the system does obey Beer's law over the concentration range 20–170 ug ferricyanide per 25ml. The molar absorbitivity is (4.28+0.02)×10³ cm² mg^?1 mole-¹.     

New reactions of nickel and cobalt with iron-cyanogen compounds and a new method of determination of ferricyan

Nickel ferrocyanide in presence of acids is oxidised by the oxygen of the air to nickel ferricyanide. Cobalt ferrocyanide is oxidised under the same conditions to a ultramarine blue substance with a slight grayish tinge. This substance is very similar to Prussian blue and to Turnbull's blue and could be called cobalt Prussian blue. This blue substance is also formed if mixtures of potassium ferrocyanide and potassium ferricyanide are precipitated with an excess of cobalt salt. This investigation led to the conclusion that the blue substance is probably not a mere mixture of cobalt ferrocyanide and cobalt ferricyanide. but the compound 6 Co₂[Fe(CN)₆]. Co₃[Fe(CN)₆]₂. A new method of the determination of ferricyan is described. Moreover, it was proved that some statements of former investigators on the reactions of nickel and cobalt with iron-cyanogen compounds are erroneous, and some iron-cyanogen compounds of nickel and cobalt described in the literature do not exist at all.     

A ferricyanide-ceriometric determination of vanadium

Oxidation of vanadyl ion by alkaline ferricyanide has been reinvestigated and a modified procedure for the volumetric estimation of vanadium, based on the titration of the resulting ferrocyanide against standard ceric sulphate, is described.     

Determination of some noble metals and copper by destructive neutron activation analysis of different matrices

Neutron activation analysis of palladium, iridium, platinum, gold, silver and copper in different matrices was carried out by using inorganic adsorbers such as molybdenum dibromide, zinc ferrocyanide and cadmium metal for their radiochemical separation. The matrices chosen to show the versatility of the method were: high-purity copper and nickel metals, NBS standard reference material SRM 1571 (Orchard leaves), Pultusk meteorite and the U. S. Geological Survey standard rock W-1. The method elaborated is very simple as it involves only a few steps and it has been shown to be accurate and capable of yielding reliable results.     

Titrimetric determination of some phenothiazine derivatives, with ferricyanide

Six phenothiazine drugs (chlorpromazine hydrochloride, promethazine hydrochloride, promazine hydrochloride, perphenazine, acetophenazine maleate and trifluoperazine hydrochloride) have been determined by titration with potassium ferricyanide in phosphoric acid medium with Methylene Blue as a screening indicator. The results were in agreement with those obtained by the official methods.