The determination of glycerol : General introduction: volumetric determination as the copper complex

A method for the determination of glycerol by means of the copper-glycerol complex is described; the complex is filtered free of excess copper(II) hydroxide and the copper is determined iodimetrically. Earlier difficulties due to adsorption of the complex are overcome by the use of glass-fibre filter discs. The method gives accurate results in the range 40-4% glycerol in the solution (400 to 40 mg glycerol in the aliquot taken).     

Absorptiometric determination of sulphide ion

An absorptiometric method is described for sulphide ion, based on the green colour which is formed when sulphide ions are treated in ammoniacal solution with iron(III) and an excess of nitrilotriacetic acid. The recommended procedure can be applied from 1200 down to 8 ppm of sulphide and is interfered with seriously only by selenite from amongst seventeen other anions examined. The colour system is stabilized by an excess of sulphite. Suggestions are made about the nature of the colour body and its mechanism of production.     

Absorptiometric determination of traces of iron extracted as ferroin thiocyanate

Iron up to 3 ppm can be absorptiometrically determined by extracting the ferroin-thiocyanate complex at pH 1 into isobutyl methyl ketone (IBMK). At this pH thiocyanate itself reduces iron(III) so reductants such as hydroxylamine are not needed. The complex is very stable and has a molar absorptivity of 20.5 x 10(3) in IBMK at 525 nm. Most of the substances associated with iron in minerals and alloys do not interfere and methods are suggested for the elimination of the effect of those which do.     

The determination of microgram and sub-microgram amounts of boron : Absorptiometric determination using curcumin

Three methods are described for the absorptiometric determination of boron present in alkaline residues in a platinum dish. These are based on the reaction of boric acid and a curcumin reagent to form the red compounds rubrocurcumin and rosocyanin The first method is suitable for quantities of the element between about 2 and 15 μg, the second is best used when between 0.5 and 4 μg are present and the third when the highest sensitivity is required, 0.01–0.2μg. The last method does not involve the use of an oxalic acid promotor and is thought to give the maximum sensitivity possible for any absorptiometric technique. The three procedures were developed and have been used over the last decade for the analysis of atomic energy materials and have received very thorough testing under routine conditions.     

Absorptiometric determination of bismuth with thorin

A simple, precise absorptiomotric method for bismuth based upon its reaction with Thorin is described. The effect of foreign elements was established.     

Adsorptive voltammetric determination of copper as its nioximate complex

A sensitive and selective stripping voltammetric ultratrace determination of copper is described, based on adsorptive accumulation of the cu(II)-nioxime complex on the surface of a hanging mercury drop electrode, followed by the reduction of the adsorbed complex during the cathodic scan. The analytical conditions for the determination of copper by differential-pulse and linear-scan absorption voltammetry have been optimized. The method is compared to the routine anodic stripping voltammetric method for copper. Its applicability to river and potable water analysis is illustrated. The detection limit, restricted by the blank, is about 0.5 microg/l.; the relative standard deviation (at microg/l. level) for a standard solution is below 5% and for water samples is 5-9%.     

Absorptiometric determination of palladium with 2,3-quinoxalinedithiol

A method is described for the absorptiometric determination of palladium, in the range 0.1-2.5 ppm, with 2,3-quinoxalinedithiol (H(2)qdt) in aqueous ethanol. The reagent, S-2-(3-mercaptoquinoxalinyl) thiuronium chloride (mgt), is hydrotysed rapidly to (qdt)(2-) at pH 10. In the presence of zinc, (qdt)(2-) is stabilized by complex formation and reagent blanks are reduced almost to zero. An anionic 1:2 complex of palladium(II) and (qdt)(-2) is formed at pH 10, having maximum absorbance at 454 nm and Sandell sensitivity index of 0.0032 mug cm (2). The reaction is moderately selective; equivalent concentrations of platinum(IV), iridiuin(IV) and rhodium(III) can be tolerated but gold(III), copper(II) and a few other metals interfere. Suggestions are made for masking interferences. The method is characterized by good precision, with a relative standard deviation of 0.25% at the 1-ppm level.     

Absorptiometric determination of hafnium with molybdophosphoric acid

Summary A sensitive method for the absorptiometric determination of hafnium has been developed. It is based on the reaction of hafnium with molybdophosphoric acid at p_H 4.0. The method follows Beer's law in the range 0–14 parts per million hafnium. Data on interfering substances are presented.

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Zusammenfassung Ein empfindliches Verfahren zur Hafniumbestimmung durch Absorptionsmessung wurde ausgearbeitet. Es beruht auf der Reaktion des Hafniums mit Molybdänphosphorsäure bei p_H 4,0. Bis 14 ppm Hf ist das Beersche Gesetz erfüllt. Störende Ionen werden angegeben.

     

Absorptiometric determination of microgram amounts of uranium with Rhodamine B

Uranium (VI) can be extracted as a complex with rhodamine B into a benzeneetherhexone solvent from a benzoate buffered solution. Optimum conditions for the colour development are defined, leading to a molar absorptivity of 102700 mmol^-1 cm² at 555 nm, the highest yet reported for a uranium complex. The determination of uranium in the range 0.02–3 μg/ml in nitrate samples is described. The relative standard deviation ranges from 20 to 0.6%. The interference of several ions is investigated.     

Mercurous nitrate as a reductimetric reagent : The determination of copper

It has been found that in the presence of excess thiocyanate ions, cupric copper will oxidise ferrous ions. Use has been made of this reaction to determine copper by titration of the ferric iron produced, with mercurous nitrate. Although this reaction is the reverse of that usually observed, where the cuprous ion reduces the ferric iron, it has been found that the large excess of thiocyanate is responsible for this effect.     

The spectrophotometric determination of copper as the 2-furoyltrifluoroacetone chelate

The copper 2-furoyltrifluoroacetone chelate may be quantitatively precipitated from aqueous solutions and extracted into organic solvents The organic extract, which is an intense green, absorbs light strongly at a wavelength of 660 mμ. Although the β-diketone is not a specific reagent, most of the other metal chelates are colorless, not extracted, or do not absorb light at 660 μ.A rapid, sensitive, and reasonably specific spectrophotometric method for the determination of copper was developed on these properties. The method is applicable to the determination of as little as one mg of copper at concentrations as low a.s 5 p.p m. Iron, vanadium, cerium, nickel, and palladium are the only serious interferences among the more common elements. The method appears suited for the determination of copper in brass samples and in aluminum based alloys.     

The extraction and determination of molybdenum as the thiocyanate complex

A method is presented for the determination of molybdenum by extraction of its thiocyanate complex with methyl isobutyl ketone. The method is accurate to ±4% or 3 μg of molybdenum, whichever is greater. The only elements which cause interference are rhenium (serious), platinum, palladium, rhodium, selenium and tellurium. The method has been applied to a number of standard samples with excellent results.     

Hydrazinium thiocyanate as a reagent for determination of copper

Hydrazinium thiocyanate, N(2)H(5)SCN, has been used for the determination of copper in copper salts. The reagent reduces the copper ions to the cuprous state and precipitates cuprous thiocyanate Cu(2)(SCN)(2), quantitatively.     

Trifluoroethylxanthate as an analytical reagent: Spectrophotometric determination of cobalt and copper as their trifluoroethylxanthates

Summary A direct spectrophotometric method has been developed for the micro-determination of Co(II) and Cu(II) as their trifluoroethylxanthates, by use of aqueous acetone medium. The reagent and methods have been found selective and sensitive for the determination of these metals in certain alloys.

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Trifluorethylxanthat als analytisches Reagens: Spektrophotometrische Bestimmung von Kobalt und Kupfer

Zusammenfassung Eine direkte spektrofluorimetrische Methode zur Mikrobestimmung von Co(II) und Cu(II) in Form ihrer Trifluorethylxanthate in wäßrigem Acetonmedium wurde ausgearbeitet. Reagens und Methode sind bei der Bestimmung der genannten Metalle in gewissen Legierungen selektiv und empfindlich.