Determination of aluminium in plutonium metal by differential linear sweep oscillographic polarography

A procedure has been developed for the polarographic determination of aluminium in plutonium. The plutonium is separated by anion-exchange in a nitrate medium, and the aluminium is determined in the eluate by use of Superchrome Garnet Y. The aluminium concentration range in the polarographed solutions is 0.020–0.800 μg/ml. The average recovery of aluminium was 99.3 %, relative standard deviation 7.2%. Of 20 common impurities found in plutonium métal, only molybdenum and titanium cause significant interference; both can be removed by ion-exchange.     

The polarography of azo dyes and their metal complexes

Summary Studies are reported of the polarography of iron and nickel in the presence of solochrome violet RS. It is shown that complexes with iron are formed at pH values in the region of 4.5 and 6.5. The former has a dye-iron combining ratio of 21, while that at pH 6.5 is 41. Simultaneous polarography of iron and aluminium in solochrome violet RS solution showed that at pH 3.5 distinct steps for both elements may be obtained, but they are not sufficiently separated for quantitative purposes.The polarographic behaviour of nickel is shown to be different from the other species studied. No dye complex is formed at pH 4.5 in acetate buffer while that at pH 6.5 has a dye-nickel combining ratio of 21. In borate buffer, however, complexes at pH 4.5 and pH 6.5 are obtained, which yield step heights proportional to nickel concentration. Reproducible values for the combining ratios of these two species were not obtained.The reactions of these elements are discussed and reference to certain theoretical aspects is made.

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Zusammenfassung Es wird über Untersuchungen zur polarographischen Bestimmung von Eisen und Nickel in Gegenwart von Solochromviolett RS berichtet. Komplexe mit Eisen werden bei pH 4,5 bzw. 6,5 mit dem Verhältnis Farbstoff- Fe=21 bzw. 41 gebildet. Bei der gleichzeitigen Polarographie von Eisen und Aluminium in einer Lösung von Solochromviolett RS werden bei pH 3,5 deutliche Stufen für beide Elemente erhalten, jedoch ist für quantitative Zwecke die Trennung nicht ausreichend. Nickel weist ein abweichendes polarographisches Verhalten auf: In Acetatpuffer wird bei pH 4,5 kein Komplex mit dem Farbstoff gebildet, bei pH 6,5 wird ein Komplex mit dem Verhältnis Farbstoff:Ni=21 gebildet; in Boratpuffer jedoch erhält man Komplexe bei beiden pH-Werten, die der Ni-Konzentration proportionale Stufenhöhen ergeben. Reproduzierbare Werte für die Verbindungsverhältnisse dieser beiden Arten konnten jedoch nicht erhalten werden. Die Reaktionen der genannten Elemente werden diskutiert und einige theoretische Hinweise gegeben.

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Dedication. This paper is dedicated to Prof. Dr. M. von Stackelberg with grateful appreciation of his friendly interest, inspiration and encouragement, and with thanks for his many acts of kindness.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

Differential capacity measurement by means of oscillographic polarography

Summary Measurement is described of the differential capacity of the electrode double-layer of the mercury electrode polarized with rectangular alternating current. The evaluation is carried out using the curves in coordinates dE/dt and E on the screen of an oscilloscope. The oscillographic measurements of differential capacity in solutions of various electrolytes and also in presence of surface active substances are compared with those obtained by bridge methods performed at adjusted adsorption equilibrium. The eventual differences in the results obtained with both methods are discussed.

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Zusammenfassung Es wurde eine oscillographische Methode zur Ermittlung der differentiellen Doppelschichtkapazität der Quecksilberelektrode ausgearbeitet, die auf der Polarisation der Elektrode mit Wechselstrom von rechteckigem Verlauf beruht. Die Messung wird an Hand der Kurven dE/dt= f(E) auf dem Bildschirm des Oscillographen durchgeführt. Die mit dieser Methode in verschiedenen Elektrolytlösungen sowie in Lösungen mit verschiedenen oberflächenaktiven Verbindungen gemessenen Doppelschichtkapazitäten werden mit den Resultaten verglichen, die mit einer Kapazitätsmeßbrücke bei eingestelltem Adsorptionsgleichgewicht erhalten wurden. Eventuelle Unterschiede in den bei Anwendung beider Methoden erreichten Meßwerten werden besprochen.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

Inorganic polarography in organic solvents-IV: polarography of metal oxinate complexes in various solvents

The polarography of 24 metal oxinate complexes extracted into chloroform, IBMK, and ethyl acetate has been investigated, a methanolic solution of lithium chloride being used as base electrolyte. Only 15 complexes gave rise to reduction waves, and interference-free determinations have been developed for indium and thallium(III) in chloroform, and for bismuth, molybdenum and uranium in IBMK. The use of ethyl acetate offered no special advantages, and was the least selective of the three solvents used.     

Intercalation of noble metal complexes in LDH compounds

Intercalation of iridium, platinum, and ruthenium complexes was carried out in [ZnAl], [MgAl], and [CuAl] LDHs structures by a new method of hydrothermal synthesis. Carbonate-free products were obtained. XRD, FTIR and EXAFS studies confirmed total anion exchange for Ir and Pt containing compounds. However, the geometry of local environment of iridium or platinum atom in the complexes appeared modified during intercalation. By thermal treatments metallic particles dispersed on oxide powder were obtained.     

Evaluation of mercury coated glassy carbon electrodes for oscillographic polarography

The suitability of a mercury film electrode formed over a glassy carbon substrate for oscillographic polarography has been studied. The data obtained show that it is possible to get well-developed oscillograms characteristic of the depolariser (in the concentration range 10^∮5–3×10^?4M) in solution which are similar to those obtained with a dropping mercury electrode. For quantitative analysis the mercury film electrode has been found to have limited applicability since the indentations have been found to be time-dependent.     

Alternating current polarography of metal carbonyl complexes in nonaqueous solvents

Using commercially available instrumentation, a supporting electrolyte and electrode system was devised which permits ac polarography of organometallic compounds, transition metal complexes, and other substances in nonaqueous solvents such as methanol, N,N-dimethylformamide, or acetonitrile. The first two solvents mentioned were found to be far superior to the latter. Tetrabutylammonium perchlorate electrolyte (0.1 M or less) in methanol, for example, affords a fairly flat baseline in the applied dc potential range of 0 to ?3 V with well-shaped voltammetric peaks for most reducible substances. A unique feature of the method, which permits one to easily obtain replicable polarograms and peak potentials, is the use of a mercury pool auxiliary electrode rather than the usual platinum or tungsten electrodes.     

The polarographic determination of aluminium : The oscillographic polarography of aluminium in calcium chloride solution

A study of the polarography of aluminium using the linear-sweep cathode ray polarograph is described. The conditions nccessasary for obtaining satisfactory aluminium waves in this medium have been established and the relationship between aluminium peak height and concentration examined. The occurrence of unexpected phenomena relating the change of step shape with varying start potential values is described and discussed and a method for overcoming the effects, by buffering, is presented     

Determination of uranium in plutonium by differential linear sweep oscillographic polarography

The polarographic behavior of uranium in hydroxylamine hydrochloride was investigated by differential oscillographic polarography. A procedure is presented for the determination of uranium in plutonium for concentrations of uranium greater than 10 p.p.m. Analyses of solutions containing 22 common impurities found in plutonium metal revealed that antimony, copper, and titanium cause significant interference. A reversible peak corresponding to a one-electron reduction was obtained with a peak potential of -0.167 V vs. Hg pool electrode. The diffusion coefficient is 0.51·10^-5 cm²/sec and the diffusion current constant is 1.59 with an average relative standard deviation of 2.28%. The peak current of uranium can be affected by hydrochloric, nitric, perchloric, and sulfuric acids, depending on the acid concentration.     

The polarographic determination of aluminium : The elimination of interfering elements and the determination ofaluminium by oscillographic polarography

A study is reported of the effect of some ion species on the determination of aluminium by osicillographic polarography under the conditions. previously established. The development of an electrolytic procedure for the removal of interfering metal ions is described and details of unsuccessful attempts to remove interference by fluoride are given. The method for the determination of aluminium is given in detail and result obtained with it are presented.     

Direct-current,normal-pulse and reverse-pulse polarography of some heavy metal—polycarboxylate complexes

Complex formation of Zn(II) and Cd(II) with polymethacrylic acid (PMA) andpolyacrylic acid (PAA) is studied by sampled direct-current, normal-pulse and reverse-pulse polarography. The combined use of these techniques serves a twofold purpose: to cover different time windows and to eliminate interferences from adsorption of the metal ion induced by the ligands. The two Zn(II) systems appear to be labile on the different time scales. The association constants (K) evaluated from potential data and those from current data show good consistency. The dependence of K on the degree of neutralization (α_n) is much stronger for PAA complexes than it is for those of PMA. With the Cd(II)—PMA system complications from induced Cd(II) adsorption are completely removed by using reverse-pulse polarography. The system is not liable and stabilities derived from potential data differ from those obtained from current data. The remaining discrepancy cannot be attributed to simple association and dissociation kinetics.     

Electrochemical properties of metal complexes of dithio-acid derivatives and their application in extraction polarography

Metal complexes with dithiocarbamic (dtc), xanthic (xan) and dithiophosphoric (dtp) acids give rise to one or more polarographic waves in dimethylformamide and in mixtures of extracting solvents and ethanol. The electrons are found to be transferred stepwise in the case of unfilled d-shell metal complexes. The shift of half-wave potential depends on the ligand, increasing in the order dtp < xan < dtc. In solvents with low solvation power the electrode processes are more reversible. The linear dependence of the limiting current on the chelate concentration has been used for determining the metal in the organic phase without re-extraction. Pb(II), Bi(III) and As(III) have been separated with dtp as extractant, and the concentrations of Co(II), Ni(II) and Zn(II) complexes (simultaneously extracted) have been determined polarographically.     

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the ruthenium(iii) bis(ethylenediamine) complex {trans-[Ru(en)₂Cl₂]@CB[8]}Cl·27.5H₂O (1), the gold(iii) diethylenetriamine complex {[Au(dien)Cl]@CB[8]}Cl₂·11H₂O (2), and the gold(iii) and platinum(ii) cyclam complexes (H₃O)₅{[Au(cyclam)]@CB[8]}Cl₈·18H₂O (3) and {[Pt(cyclam)]_0.11(H₂cyclam)_0.89@CB[8]}Cl₂·16H₂O (4), respectively, where cyclam is the tetraazamacrocyclic ligand, were synthesized. The inclusion compounds were synthesized both directly starting from CB[8] and the metal complexes with polyamines (en or dien) and by the two-step method with the use of the cyclic polyamine ligand (cyclam) pre-included into the cavity of the macrocycle. The inclusion compounds were characterized by X-ray diffraction (1, 2, and 4), IR spectroscopy, electrospray ionization mass spectrometry, UV-Vis spectroscopy, and thermogravimetric analysis.     

Simultaneous thermal analysis/mass spectrometric investigations on the thermal behaviour of noble metal complexes

The results of investigations on the thermal behaviour of three selected noble metal complexes, performed by means of simultaneous thermal analysis/mass spectrometry are discussed. The thermal analysis data, such as the initial temperatures for the beginning of the weight loss, the amounts of the weight loss, as well as the characteristic DTG and DTA temperatures, are tabulated and the simultaneously recorded electron impact mass spectra are interpreted. The temperature-dependent formation and cleavage of typical complex-structure-related substituents is described and established by the evaluation of the course of the corresponding ion-current intensities.     

Study of mixed complexes by polarography: cadmium-glycine-methionine and cadmium-glycine-ethylenediamine complexes

The mixed complexes of cadmium with glycine and methionine and glycine and ethylenediamine have been studied by polarography and the stability constants of the various species formed have been evaluated.     

Fragmentation of doubly charged noble metal clusters

The dissociation patterns of doubly charged noble metal clusters (M) _n ⁺⁺ to two singly charged clusters, (M) _m ^Emphasis>1/+ and (M) _m ^Emphasis>2/+ have been investigated using a double focusing mass spectrometer. They are compared with the dissociation patterns from singly charged clusters. The dissociation probabilities to (M) ₃ ⁺ and (M) ₉ ⁺ were large and the odd-even alternations were observed in both patterns.