Analytical applications of copper(II) and copper(I) in acetonitrile: potentiometric and spectrophotometric determination of dithiocarbamates

The use of copper(II) perchlorate and tetra-acetonitrilocopper(I) perchlorate (in acetonitrile) for the potentiometric and spectrophotometric determination of dithiocarbamates in acetonitrile medium is described. The proposed methods are simple, accurate and reliable and show promise of wide applicability. They are recommended for routine determination of dithiocarbamates. Their advantages over the carbon disulphide evolution method, commonly employed for the determination of these compounds, are discussed.     

Determination of copper(I) and copper(II) ions after complexation with bicinchoninic acid by CE

A facile, sensitive, and selective method was developed for the simultaneous separation and determination of copper(I) [Cu(+)] and copper(II) [Cu(2+)] ions using CE with direct UV detection. The copper ions were complexed with a 1.5 mM bicinchoninic acid disodium salt solution at pH 8.7 prior to analysis. Acetate buffer (2 mM) was used as the CE running buffer. Parameters affecting CE separation such as sample pH, applied voltage, concentration of complexing agent, nature of the buffer solution, and interferences by other metal ions, were evaluated. The LODs for Cu(+) and Cu(2+) were 3.0 and 2.5 microg/mL (S/N = 3), respectively. The developed method allows the simultaneous determination of Cu(+) and Cu(2+) in less than 5 min with RSDs of between 5.3 and 9.5% for migration time and between 3.4 and 9.7% for peak areas, respectively. At optimum conditions, the percentage recoveries of Cu(+) and Cu(2+) were found to be 99.4 and 99.5%.     

Spectrophotometric study of coproporphyrin-I complexes of copper(II) and cobalt(II)

The reagent 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I (CPI) was used for the spectrophotometric determination of copper(II) and cobalt(II) in the presence of pyridine and imidazole catalysts. Optimum conditions were investigated and the methods were applied to the determination of parts per billion levels of copper(II) and cobalt(II). The Sandell sensitivities of the recommended procedures were 0.568 μm cm⁻² and 0.464 μg cm⁻² (for A = 0.001) for copper and cobalt, respectively. The relative standard deviations were 2.0% for copper and 1.0% for cobalt. The kinetics of the reaction of CPI with copper(II) and cobalt(II) in the presence of the catalysts and the influence of the temperature were studied, and their kinetic constants determined.The influence of light on the photodecomposition of CPI was also studied.     

Analytical applications of ternary complexes-II Spectrophotometric determination of copper as rose bengal bisphenanthrolinium copper(II)

A ternary complex system, [(Cu.phen(2))Rose Bengal], is proposed for the determination of traces of copper ion. The reaction is rendered specific for copper amongst 56 cations and most anions by extraction of bis(2,9-dimethyl-1,10-phenanthrolinium) copper(I) from an EDTA medium. Because of the high molar absorptivity, 62,500, solutions containing 0.002 ppm of copper may be analysed without difficulty. The colour system is stable for a period of days.     

Amperometric determination of thioacetamide with copper(I)

A method is given for the amperometric determination of thioacetamide (TAA) based on the reaction of TAA with copper(I) in ammoniacal solution. The reduction current due to the copper(I) is used to determine the end-point. The determination is carried out at constant temperature (25°), pH 8.0-9.8 (ammonia-urotropine buffer), and at constant potential (−0.6 V vs. S.C.E.), with a dropping mercury electrode as cathode and a saturated calomel electrode as anode. The solution is deaerated by a stream of electrolytically generated hydrogen. The titrations are carried out simply and rapidly and the results are fairly reproducible. The error is generally 1.0% for amounts of TAA ranging from 0.07 to 1.8 mg.     

Adsorptive stripping voltammetric determination of copper(II) ion using phenyl pyridyl ketoneoxime (PPKO)

A sensitive and selective procedure is presented for the voltammetric determination of copper(II) ion. The procedure involves an adsorptive accumulation of Cu2+-PPKO on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of reduction current of adsorbed complex at about -0.30 V (vs. SCE). The optimum conditions for the analysis of copper(II) ion include pH (5.8-7.0), 60 microgM PPKO and an accumulation potential of -0.5 V (vs. SCE). The peak current is proportional to the concentration of copper over the range 0.3-76 ng mL(-1) with a detection limit of 0.01ng mL(-1) with an accumulation time of 60 s. The speciation of different forms of complex between copper(II) ion and PPKO, using the Best (Martell program), followed pH measurement were examined. The method was applied to the determination of copper(II) ion content in real samples successfully.     

The titrimetric determination of copper(I), copper(II) and copper metal in admixture

Summary Copper(I) can be determined in the presence of copper(II) by oxidation with an excess of potassium iodate, the copper(II) being masked with oxalate. The unconsumed iodate is determined iodimetrically and the total copper is then determined on the same solution by demasking with acid and iodide, followed by iodimetric titration. The method can be extended to include elemental copper which can be separated from copper(I) and copper(II) oxides by dissolving the oxides in an ammonium chloride-ascorbic acid solution. The separated copper metal can then be determined by the iodate procedure. The methods are accurate and reproducible and have been applied to the determination of commercial copper(I) chloride, copper powder and partially oxidized copper powder. The relative standard deviation is about 0.35% in the range of 5.8–100 mg of Cu.

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Trimetrische Bestimmung von Kupfer(I), Kupfer(II) und metallischem Kupfer in Gemischen

Zusammenfassung Cu(I) kann in Gegenwart von Cu(II) durch Oxidation mit überschüssigem Kaliumiodat unter Maskierung des Cu(II) mit Oxalat bestimmt werden. Das unverbrauchte Iodat wird iodometrisch erfaßt und anschließend Gesamtkupfer in derselben Lösung iodometrisch nach Demaskierung mit Säure und Iodid bestimmt. Das Verfahren kann noch auf metallisches Kupfer erweitert werden, das von Cu(I)- und Cu(II)-oxiden abgetrennt wird, indem man letztere in Ammoniumchlorid-Ascorbinsäurelösung löst. Das elementare Kupfer wird dann mit Iodat bestimmt. Die Methoden sind genau und reproduzierbar und sind zur Analyse von handelsüblichem Kupfer(I)-chlorid, Kupferpulver und teilweise oxidiertem Kupferpulver angewendet worden. Die relative Standardabweichung liegt im Bereich von 5,8–100 mg Cu bei 0,35%.

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This paper is respectfully dedicated to Professor Dr. Herbert Weisz on the occasion of his 60th birthday.

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The authors are grateful to Emeritus Professor Ronald Belcher for his interest in this work.     

Voltammetric behaviour of copper(iii) and its analytical applications

Copper(II) and copper(III) complexes with periodate or tellurate ligands are electroactive at a smooth platinum electrode, giving an anodic, cathodic or cathanodic wave in the presence of alkaline hydroxide solutions containing copper(II), copper(III), or copper(II)-copper(III) species, respectively. The corresponding limiting currents are diffusion-controlled. The following analytical applications are proposed: (a) amperometric titration of copper(III) solutions; (b) voltammetric determination of copper. Results of amperometric titrations of copper(III) were similar to those by an established procedure. Voltammetry of copper(II) allows the metal to be determined down to concentrations of 1·10^-5M, even in the presence of different ions; the procedure can be applied to such heat-transfer media for nuclear reactors as sodium and potassium metals and their hydroxides.     

Extraction-spectrophotometric determination of traces of gold in copper in silver, lead, blister copper, copper concentrate and anode slime with 4,4'-bis(dimethylamino)-thiobenzophenone

A sensitive spectrophotometric method has been developed for the determination of gold in copper, silver, lead, blister copper, copper concentrate and anode slime. Optimal conditions have been established for the extraction and determination of gold. Gold is extracted as its bromo complex with tri-n-octylamine and determined photometrically with 4,4'-bis(dimethylamino)thiobenzophenone; the absorbance of the organic phase is measured at 540 nm and the apparent molar absorptivity is about 1.2 x 10(5) 1.mole(-1). cm(-1). As little as 0.1 or 0.2 ppm of gold in these materials can be determined.     

Determination of copper(II) based on its catalytic effect on thiosemicarbazide-H(2)O(2)-CTMAB chemiluminescence reaction

A novel chemiluminescence (CL) reaction, thiosemicarbazide (TSC)–H₂O₂, for the determination of copper at nanogram per milliliter level in batch type is described. The method is based on the catalytic effect of copper(II) on the oxidation of TSC with hydrogen peroxide to produce light emission. The emitted light was observed by using a conventional fluorescence detector. In the optimum conditions, calibration graph was linear in the range of 0.1–1.3 ppm. The limit of detection was 10 ppb. The relative standard deviation for five determinations of 0.5 ppm copper(II) was 1.93%. The proposed method permitted the selective and sensitive determination of Cu(II) in human hair and wheat flour with sufficient precision. The possible mechanism for the new chemiluminescence reaction was also discussed.     

Ion-pair extraction and determination of copper(II) and zinc(II) in environmental and pharmaceutical samples.

Copper and zinc were extracted from salicylate solution into Aliquat 336 dissolved in toluene and determined in the organic phase spectrophotometrically using 1-(2-pyridylazo)-2-naphthol. The determination of copper and zinc was also carried out titrimetrically or by atomic absorption spectrometry after stripping the metal ions from the organic phase. The method permits the determination of copper and zinc in environmental and pharmaceutical samples. The standard deviation and relative standard deviation are 0.052 micrograms and 0.69%, respectively, for copper and 0.041 micrograms and 0.60%, respectively, for zinc.     

Oxidation of some sugars with copper(III)

The titrimetric determination of glucose, fructose, mannose, galactose, arabinose, xylose and sucrose with potassium ditelluratocuprate(III) is described. On heating, pentoses and hexoses consume 20 and 24 equivalents of copper(III) per mole respectively, and sucrose consumes 48 equivalents.     

Gravimetric determination of copper(II) with p-aminobenzoic acid

A method has been developed for the gravimetric determination of 20-100 mg of copper(II) with p-aminobenzoic acid. Ag, Hg(II), Pb, Al, Fe(II), Bi, Sb(III) and Sn(II) interfere, but Zn, Co(II), Ni and Cd do not. The precipitate can be weighed after drying at 80-100 degrees , or can be ignited to copper(II) oxide at temperatures above 400 degrees , and weighed in this form.     

Determination of trace amounts of copper with 4-(2-pyridylazo)resorcinol by solid phase spectrophotometry

A determination method for traces of copper by Solid-Phase Spectrophotometry (SPS) has been developed. It is based on the fixation of copper(II) as 4-(2-pyridylazo)resorcinol complex on a styrene-divinylbenzene anion-exchange resin. The resin phase absorbances at 525 and 800 nm are measured directly, and the determination of copper (with a RSD of 1.8%) is possible in the range of 0.3–4.5 μg L^?1. The method has been applied to the determination of copper in different samples, i.e. mushrooms, tea, drugs and waters.     

Electrochemical synthesis and structural characterization of a novel mixed-valence copper(I)-copper(II) complex: {[bis(ethylenediamine)copper(II)] bis[diiodocuprate(I)]}

A novel, mixed-valent copper(I)-copper(II) complex, {[bis(ethylene-diamine)copper(II)] bis[diiodocuprate(I)]} (1), has been prepared by electrochemical dissolution of a sacrificial copper anode in a solution of ethylenediamine (en), I2 and tetraethylammoniumperchlorate (TEAP) as supporting electrolyte in acetonitrile (AcN)and characterized by single-crystal X-ray structure determination. The crystal structure of the complex 1 shows that it consists of a CuI2 polymer formed from I- ligands bridging Cu(I) ions, with a nearly square planar geometry of bivalent Cu(II) atoms chelated by two ethylenediamine ligands. The results also show that direct electrosynthesis of the complex had high current efficiency, purity and electrolysis yield.     

Colchiceine as an extractive indicator in the determination of copper(II)

Colchiceine, a new extractive indicator, is satisfactorily used in the determination of copper(II). A highly sensitive greenish yellow complex is formed with copper, which is extractable into chloroform. The results are comparable in sensitivity and selectivity with those of its precursors.     

The determination of traces of thiocyanate and copper(II) ions by cathodic stripping voltammetry

Cathodic stripping methods are described for the determination of traces of thiocyanate ions down to 2 × 10^-8 mol l^-1 and Cu(II) ions down to 1 × 10^-8 mol l^-1. The method involves electrolytic accumulation of copper(I) thiocyanate on the surface of a hanging mercury drop electrode followed by stripping of the deposit during the cathodic scan. For the determination of thiocyanate, a copper amalgam electrode can be used. Examples of application of the method for the determination of traces of thiocyanate in common salts, in saliva and urine as well as for the determination of copper(II) ions in tap water are described.     

Extraction and spectrophotometric determination of copper with thiobenzoylacetone (3-mercapto-1-phenylbut-2-en-1-one)

The copper(II)-thiobenzoylacetone complex, extracted into benzene, is used for photometric determination of copper at 410 nm after excess of reagent has been removed by scrubbing with a buffer at pH12. The extraction is quantitative over a broad pH range (3.5-9.5). The method is highly sensitive for the determination of copper.     

Chemiluminescence investigation of NH(2)OH-fluorescein-Cu(2+) system and its application to copper analysis in serum

A novel chemiluminescent system, fluorescein-NH(2)OHOH(-), was developed for the determination of copper(II) in serum. A weak light emission arises from hydroxylamine in the presence of the organic reagent fluorescein in basic aqueous solution. Under the conditions of 1.2 x 10(-3) mol l(-1) NH(2)OH and 5 x 10(-3) mol l(-3) fluorescein, the light intensity is linearly dependent upon the concentration of copper(II) within the range 1-20 ppb. The relative standard deviation of the determination of copper(II) is 4.2% (n = 13) and the detection limit is 0.5 ppb. The system is highly selective for copper except in the presence of iron(II,III) and cobalt(II). In conjunction with potassium fluoride as masking agent, the method was successfully applied to the determination of microamounts of copper(II) in serum. A mechanistic study of the chemiluminescence reaction is also discussed.     

Complexation of copper(II) with 3-(2-hydroxyphenylazo)pentadione-2,4

It is shown that 3-(2-hydroxyphenylazo)pentadione-2,4 (H₂L) can exist in three tautomeric forms (enol-azo, keto-azo, and hydrazo). The effective atomic charges in the tautomeric forms of H₂L are calculated by the Hückel MO LCAO method. The molar fractions and molar absorptivities of the tautomers at different pH are found. The complexation of copper(II) with H₂L is studied by spectrophotometry. Beer’s law is obeyed for 0.51–5.12 μg/mL of copper. The assumed complex structure is given. The effect of foreign ions and masking agents on the complexation is studied. A procedure for the photometric determination of copper(II) in zinc-based alloys is proposed. Original Russian Text ? S.R. Gadzhieva, T.M. Mursalov, K.T. Makhmudov, F.G. Pashaev, F.M. Chyragov, 2006, published in Zhurnal Analiticheskoi Khimii, 2006, Vol. 61, No. 6, pp. 598–603.