Separation and micro-identification of metallic ions by ring oven technique. I

Summary Attempts to separate Hg(I), Pb(II), Ag(I), Hg(II), Bi(III), Cu(II), Cd(II), As(III), Sb(III) and Sn(II) in ternary, quaternary and quinary mixtures by the Weisz ring oven technique have been made, using oxalate as complexing agent and aqueous ethanol as solvent. It is found, in general, that addition of oxalate as complexing agent enables separations to be carried out which do not occur in the uncomplexed solutions. The effect of adding varying concentrations of the complexing agent to the solutions has been studied. The sequences of separation in ternary, quaternary and quinary mixtures with varying concentrations of the complexing agent have been described.

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Zusammenfassung Es wurde versucht, Hg(I), Pb(II), Ag(I), Hg(II), Bi(III), Cu(II), As(III), Sb(III) und Sn(II) in Drei-, Vier- und Fünfstoffgemischen unter Verwendung von Oxalat als Komplexbildner und wäßrigem Äthanol als Lösungsmittel nach der Ringofentechnik vonWeisz zu trennen. Im allgemeinen ermöglicht die Komplexierung mit Oxalat Trennungen, die sonst nicht durchführbar sind. Die Einwirkung verschiedener Konzentrationen des Komplexbildners auf die Probelösungen wurde geprüft. Die Reihenfolge der Trennung aus den angeführten Mischungen bei verschiedener Oxalatkonzentration wird angegeben.

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Résumé On a essayé de réaliser la séparation de Hg-I, Pb-II, Ag-I, Hg-II, Bi-III, Cu-II, Cd-II, As-III, Sb-III et Sn-II dans des mélanges ternaires, quaternaires et quinquénaires, au moyen de la technique du four annulaire deWeisz, en utilisant des oxalates comme agents complexants et l'éthanol aqueux comme solvant. On a trouvé que, généralement, l'addition d'oxalates comme agents complexants oblige à effectuer des séparations qui ne se rencontrent pas dans les solutions non complexées. On a étudié l'effet de l'addition de concentrations variables de l'agent complexant aux solutions. On a décrit les étapes de la séparation dans les mélanges ternaires, quaternaires et quinquénaires pour des concentrations variables de l'agent complexant.

     

Investigations on the effect of aqueous acetone medium on separation of metal ions on Chelex 100 ion-exchanger

The use of glycine as a complexing agent in acetone-water medium for the separation of metal ions with Chelex 100 chelating resin has been investigated. The affinity of metal ions for Chelex 100 in the presence of glycine in acetone-water and aqueous medium was determined as a function of acidity and it was established that the presence of acetone is an essential factor in production of differentiation in the selectivity and for consequent separation of a number of mixtures of metal ions [Cu(II)Co(II); Cu(II)Al(III)Pb(II); Cu(II)Ni(II)Co(II); Cu(II)Ni(II)Pb(II)]. The mechanism of the effect of acetone is discussed.     

Biacetyl monooxime ferrocenoylhydrazone and its complexing properties

Biacetyl monooxime ferrocenoylhydrazone has been synthesized and studied by ¹H NMR, IR, and electronic spectroscopy. The electronic absorption spectrum of the title compound in the UV and visible regions has been found to depend on the solvent polarity and pH. Most favorable structures of the hydrazone in solution and gas phase have been determined by quantum chemical calculations. The complexing ability of biacetyl monooxime ferrocenoylhydrazone toward copper(II), nickel(II), and zinc(II) ions has been estimated.     

New masking procedure for selective complexometric determination of copper(II)

A study has been made of a new masking procedure for highly selective complexometric determination of copper(II), based on decomposition of the copper-EDTA complex at pH 5-6. Among the various combinations of masking agents tried, ternary masking mixtures comprising a main complexing agent (thiourea), a reducing agent (ascorbic acid) and an auxiliary complexing agent (thiosemicarbazide or a small amount of 1,10-phenanthroline or 2,2'-dipyridyl) have been found most suitable. An excess of EDTA is added and the surplus EDTA is back-titrated with lead (or zinc) nitrate with Xylenol Orange as indicator (pH 5-6). A masking mixture is then added to decompose the copper-EDTA complex and the liberated EDTA is again back-titrated with lead (or zinc) nitrate. The following cations do not interfere: Ag(+), Hg(2+), Pb(2+), Ni(2+), Bi(3+), As(3+), Al(3+), Sb(3+), Sn(4+), Cd(2+), Co(2+), Cr(3+) and moderate amounts of Fe(3+) and Mn(2+). The notable feature is that consecutive determination of Hg(2+) and Cu(2+) can be conveniently carried out in the presence of other cations.     

The separation of cobalt,manganese and sodium by electrophoretic focussing of ions

Electrophoretic focussing of cobalt(II), manganese(Il) and sodium(I) ions was investigated with EDTA as a complexing agent. Excellent separations of binary mixtures Co/Mn and Mn/Na are described, even for very unfavourable activity ratios. Separation of Co/Mn/Na is only satisfactory if the activities are of the same order of magnitude.     

Preconcentration and separation of copper (II) with solvent extraction using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

Preconcentration and separation with solvent extraction of Cu(II) from aqueous solution using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane (H₂L) as the new extractant has been studied. Separation of Cu(II) from other metal ions such as Cd(II), Ni(II), Zn(II), Pb(II), Cr(III), Co(II) and Mn(II) at aqueous solutions of various pH values and complexing agent H₂L, has been described. The possible extraction mechanism and the compositions of the extracted species have been determined. The separation factors for these metals using this reagent are reported while efficient methods for the separation of Cu(II) from other metal ions are proposed. From the loaded organic phase, Cu(II) stripping was carried out in one stage with different mineral acid solutions. The stripping efficiency was found to be quantitative in case of HNO₃ and HCl. From quantitative evaluation of the extraction equilibrium data, it has been deduced that the complex extracted is the simple 1:1 chelate, CuL. The extraction constant has a value of logK_ex=−4.05±0.04.     

Solvent extraction of Zn/II/ with 1,2,3-benzotriazole into n-hepatanol

A method based on solvent extraction has been developed for the radiochemical separation of Zn/II/ from other elements employing 1,2,3-benzotriazole as a complexing agent and n-heptanol as an extractant. Optimum conditions for the extraction have been established. The effect of various anions and cations on the extraction coefficient value of Zn/II/ has been studied. The stoichiometry of the metal to reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 12.     

Factorial designs applied to the development of a capillary electrophoresis method for the analysis of zinc, sodium, calcium and magnesium in water samples

The aim of this work was to study the influence of several both chemical and instrumental variables for the development of a new capillary electrophoresis (CE) method for the determination of zinc, sodium, calcium and magnesium in water samples by using 1,10-phenanthroline as complexing agent and UV photometric detection at 214 nm. Due to the number of parameters involved and their interactions, factorial experimental designs at two levels have been applied to investigate the influence of several experimental variables (concentration of complexing agent, concentration of a visualisation agent, pH, sample introduction, applied voltage and capillary length) in sets of several capillary electrophoretic responses. The method was applied to the simultaneous determination of Na(I), Ca(II), Mg(II) and Zn(II) in drinking water with satisfactory results and a detection limit of 32 ng ml⁻¹ for Zn(II) was obtained.     

Separation of uranium(VI) from Fe(II), Ni(II), Co(II) and Cu(II) by electrophoresis using diethyldithiophosphoric acid

Paper electrophoresis has been used for uranium(VI) separation from Fe(II), Co(II), Ni(II) and Cu(II). The background electrolyte (0.1M HNO₃-NaNO₃) at different pH values contains diethyldithiophosphoric acid as complexing agent. A plot of mobility versus pH is used to obtain information on the formation of dithiophosphate complexes and to compute the stability constant of an uranyldiethyldithiophosphate complex.     

Chromatographic separation of ions in presence of oxalate,tartrate and citrate,with aqueous ethanol as solvent

The paper Chromatographic separation of Ag, Hg, Pb, Bi, Cu, Cd, Co, As(III), Sb(III) and Sn(II) in mixtures of 3, 4 or 5 of these ions has been studied in the absence and presence of oxalate, citrate and tartrate with aqueous ethanol as solvent.     

Study of solvent-solvent interaction by paper chromatography. I. Dimethyl sulphoxide-water system

Summary The interaction between dimethyl sulphoxide (DMSO) and water, occurring when the two liquids are mixed together, has been studied: 1. by the measurement of the rate of migration of the different solvent mixtures, over the whole concentration range, on paper chromatograms, and 2. by observing the paper chromatographic behaviour of hexacyanoferrate II anions when these mixtures are used as mobile phases. The rate of migration gives a very pronounced maximum at the solvent concentration which corresponds to the composition DMSO·H₂O. The chromatographic behaviour of the hexacyanoferrate II ion besides confirming this conclusion shows the existence of three distinct zones of differing solvent structure and solvating behaviour.     

Investigations on the usefulness of tiron in separation of metal ions on the macroporous anion-exchanger amberlyst A-26

The possibility of application of a sulpho-derivative of an aromatic organic complexing agent-tiron-for separation of cations on the macroporous anion-exchanger Amberlyst A-26 has been investigated. Comparative results obtained with Amberlite IRA 400 have proved the macroporous exchanger to be the more useful. The dependence of retention on pH obtained has been established by the batch method for: Ag, Ni, Co(II), Mn(II), Zn, Cd, Pb, Cr(III), Fe(III), Ga, Al, In, Bi, Ti(IV), V(V) By taking advantage of selectivity differences, the following mixtures have been separated: AlGa, AlTi(IV), Ti(IV)Ni, NiFe(III), NiFe(III)Ti(IV).     

碘的阴极溶出伏安法研究

本文研究了碘在悬汞电极上的阴极溶出行为。提出了直接以络合剂(EDTA,DTPA,DCTA)为电解底液便可有效地消除铅、镉、铜等重金属元素的干扰。测定检出限为6.3×10^-9M。方法可不经分离富集直接测定饮用水和食盐中的痕量碘。     

Application of the zone melting technique to metal chelate systems-V Zone chromatographic separation of metal chelates on columns of some inert solid solvents

Binary mixtures of acetylacetone and 8-hydroxyquinoline chelates of copper(II), nickel(II), cobalt(II) and cobalt(III) were processed by zone-chromatography on columns of some naphthylalkyl ethers as inert solid solvents. The metal chelates were separated to give chromatograms on the columns according to the ratio of their distribution coefficients. Distribution coefficients of metal ions varied with the type of chelating agent used and the solid solvent, and were found to be strongly affected by operating conditions, especially zone length, zone travelling speed and initial concentration of the metal chelate.     

Metal Ion Chelation Chromatography on Complexon Sorbed Stannic Silicate

Abstract

Stannic silicate has been sorbed with complexones like xylenol orange, eriochrome black T and 1,10-phenanthroline for use as a chelate ion exchanger. The sorption capacity for different metals has been worked out. Kd values have been determined. Xylenol orange was used for the separation of Th(IV) from Cd(II) and Zn(II) and Cu(II) from Cd(II) and Zn(II), 1,10 phenanthroline for the separation of Fe(II) from Fe(III). These separations are based on the stabilities of the various complexes formed by the interaction of metal inns with complexones. By elution of metal ions which forms less stable complexes with the complexones no evidence of complexing agent in the eluate was found.     

Synthesis, characterization, and thermal study of polyaniline composite with the photoadduct of potassium hexacyanoferrate (II) involving hexamine ligand

The present paper involves the synthesis of polyaniline (PANI) composite with photoadduct of potassium hexacyanoferrate (II) involving hexamine as a ligand and cobalt chloride as a complexing agent via in situ oxidative polymerization by ammonium persulphate. The photoadduct has been synthesized by photoirradiation followed by substitution with the hexamine ligand. The final product has been isolated by using CoCl₂ as complexing agent. Viscosity average molar mass has been determined by viscosity method using Ostwald’s viscometer. The photoirradiation, substitution, and successful synthesis have been proved by recording pH, UV–visible spectra before and after irradiation, and FTIR of the photoadduct. The composite based on the synthesized photoadduct has been subjected to FTIR, X-ray diffraction, and SEM characterization techniques. Thermal analysis has been done by using TG and DSC technique. FTIR absorption peaks confirm the insertion of photoadduct in the backbone of PANI. SEM of the composite also supports its successful synthesis. The XRD of photoadduct shows crystalline structure, which has remained dominant in the composite, hence proving the successful synthesis of PANI composite with photoadduct. Thermal analysis shows high thermal stability of photoadduct which in turn has improved the thermal stability of PANI composite, therefore, shows the potential of composite for high-temperature application purposes.     

络合萃取-在线衍生土壤酸性除草剂条件选择与优化

以Na4EDTA为络合剂,以五氟苄基溴为衍生试剂,采用快速溶剂萃取仪萃取,同时实现土壤酸性除草剂的络合萃取在线衍生,并以气相色谱-质谱(NCI源)进行检测。对络合条件、衍生条件、萃取条件、离子源选择进行了优化。方法的回收率为75%～95%、相对标准偏差为6.7%～13%、检测限2.8～8.4μg/Kg。     

Ligandless,deep eutectic solvent‐based ultrasound‐assisted dispersive liquid‐liquid microextraction with solidification of the aqueous phase for preconcentration of lead,cadmium, cobalt and nickel in water samples

A green and efficient sample preparation method using a deep eutectic solvent‐based ultrasounds‐assisted dispersive liquid–liquid microextraction with solidification of the aqueous phase followed by high performance liquid chromatography analysis was developed for preconcentration and determination of heavy metals in environmental samples. In the proposed method, a novel, low density deep eutectic solvent was prepared by mixing trihexyl(tetradecyl)phosphonium chloride and thiosalicylic acid at a molar ratio of 1:2 and used both as an extractant and complexing agent. Ultrasound was used to disperse the extractant in the aqueous phase of the sample. Then, the phases were separated by centrifugation, after which the aqueous phase was frozen and the surface extractant phase was dissolved in a small volume of acetonitrile and subjected to liquid chromatographic analysis. The proposed method provided precisions (relative standard deviation, n = 5) in the range of 2.6–4.7%. The limit of detection were 0.05, 0.13, 0.06, and 0.11 µg/L for Pb(II), Cd(II), Co(II), Ni(II), respectively. The enhancement factors were equal to 154, 159, 162, and 158 for lead(II), cadmium(II), cobalt(II), and nickel(II), respectively. The accuracy of the proposed method was evaluated using certified reference materials (CA011b – hard drinking water, NIST 1643e – trace elements in water, TMRAIN‐04 – simulated rain sample).     

The influence of complexing agents on the effectiveness of electrochemical masking with anionic surfactants in anodic stripping voltammetry

The influence of sodium dodecyl sulphate, sodium dodecyl sulphonate and sodium stearinate on the anodic stripping peaks of Tl(I), Pb(II), Cd(II), Cu(II) and In(III) was investigated. The supporting electrolytes were 0.5M sodium sulphate solution, 0.2M citrate solution (pH 3.7, 4.6 and 7.3), 0.5M tartrate solution (pH 4.4) and 0.1M solution of EDTA (pH 4.4). The composition of complex compounds forming in a solution under experimental conditions was defined. The conditions of ion reduction of metals on hanging mercury electrode during the electrolytical deposition were investigated. The investigation included an analysis of voltammetric curves of the metal ions. The obtained results suggest that "electrochemical masking" is much stronger in electrolytes containing a complexing agent than in the sodium sulphate solution. The influence of the complexing agent may not be explained in terms of the interaction between the form of the complex and the charge of the adsorbed surfactant particles; rather the complexing process is connected with indirect inhibition, i.e., by decreasing the rate of charge transfer reaction.     

Square wave adsorptive stripping voltammetry of molybdenum(VI) in continuous flow at a wall-jet mercury film electrode sensor

An adsorptive stripping voltammetry method for the determination of traces of molybdenum(VI) in flowing solution at a wall-jet electrode sensor has been developed. After adsorption of a molybdenum complex on a wall-jet mercury film electrode, the complex is reduced by a square wave scan. More satisfactory results were obtained using 8-hydroxyquinoline as a complexing agent in nitrate medium than using Toluidine Blue in oxalic acid. Enhanced sensitivity was achieved by optimizing adsorption time and square wave parameter values. The detection limit of Mo(VI) was found to be at the nanomolar level. Interference of some other metallic species in the determination of nanomolar Mo(VI) was also investigated: Cu(II), Zn(II), Mn(II) do not interfere at 10 muM, whereas 1 muM FeEDTA(-) causes an increase in peak current. This iron interference was removed effectively with citric acid.