Application of the group substoichiometric separation of gold,mercuric, and cupric diethyldithiocarbamates to determining them by means of activation analysis

The substoichiometric method has been applied to group separation. By a single extraction gold and mercury were separated quantitatively, and copper substoichiometrically, at the same time. Zinc diethyldithiocarbamate has been used as the chelating agent. The group of elements was separated from 2N H₂SO₄ and 0.1N HClO₄ medium. This method of group separation was applied to the activation analysis of biological materials and metallic tin.     

Relative silver(I) ion binding energies of α-amino acids: A determination by means of the kinetic method

The relative silver(I) ion binding energies of 19 α-amino acids have been measured by means of the kinetic method. In general, they are similar to the relative copper(I) ion binding energies of corresponding amino acids although there are differences that can be accounted for by differences in silver(I) and copper(I) chemistry. The correlation with proton basicities is comparatively poorer. Again, the differences between silver(I) and proton binding can be attributed to differences in silver(I) and proton chemistry. The relative silver(I) binding energies measured are best described as relative basicities or ΔΔG _Ag ^° ’s. The observed internal consistency during construction of a silver(I) ion basicity ladder implies that ΔΔS _Ag ^° is approximately zero except when histidine and lysine are involved. For 16 α-amino acids, their relative silver(I) ion basicities ≈ relative silver(I) ion affinities or ΔΔG° _Ag ≈ ΔΔH _Ag ^° .     

Reactions of anionic porphyrin with group 11 elements: a spectrophotometric and electrospray ionization mass spectrometry study

The reaction of 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I (CPI) with the elements of 11 group have been studied. CPI is an anionic porphyrin that slowly reacts with copper ion to form Cu^IICPI and with silver ions to form Ag^IICPI, Ag^IIICPI complexes and colloidal silver. Gold ions do not form complexes with CPI, but, in the main, colloidal gold and some CPI-N-oxide. The kinetics of the reactions with copper and silver were spectrophotometerically studied and the rate constants were calculated. The identification and characterization of this water-soluble anionic porphyrin and its metal complexes have been performed by electrospray mass spectrometry (ESI-MS) that proved to be an excellent method for these determinations. The multiple charged parent ions for metal free ligand and their metal complexes were identified.     

Determination of caesium microamounts by isotope dilution with substoichiometric separation

Selectivity of isotope dilution analysis with substoichiometric separation for caesium determination has been investigated. Caesium can be extracted with a substoichiometric amounts of bis 1,2-dicarbollylcobaltate in nitrobenzene in the presence of dibenzo-18-crown-6. The method is selective. Other metal ions (K⁺, Na⁺, Mg²⁺, Ca²⁺, Fe³⁺, Al³⁺) do not interfere.     

Extraction of metals by neutral sulfur-containing extractants: Part I. o-isopropyl-n-ethylthiocarbamate

The formation of neutral mixed complexes of the MX_mS_p type (where M is a metal ion with m⁺ charge, X the inorganic anion, and S the sulfur-containing extractant) allows a selective extraction of various elements. The extraction of many metals from mineral acid solutions or from halide-sulfuric acid mixtures by 0.05 M O-isopropyl-N-ethylthiocarbamate(IPETC) solution in chloroform has been studied. (IPETC) possesses very high selectivity for silver and mercury ions in extractions from HNO₃, H_{2)SO4, HClO4 and HCl solutions. In addition to silver and mercury, Cu, Au, Tl and Se are readily extracted from solutions containing bromide. From iodide solutions, copper, gold and thallium ions may be selectively extracted because silver and mercury cannot be extracted at concentrations of iodide above 0.1 M.(IPETC} extracts metals as mixed complexes, containing the halide and apparently the extractant in the molecular form.     

Substoichiometric speciation for inorganic arsenic and methylated arsenic and its application to samples of marine organisms

A substoichiometric isotope-dilution method is described for the determination of monomethylarsonate, MeAs(V), and dimethylarsinate, Me₂As(V). After the separation of MeAs(V) and Me₂As(V) by extraction as their iodides into benzene, these methylated arsenic species are complexed with a substoichiometric amount of diethyldithiocarbamate in benzene, and the uncomplexed methylarsenic species are removed. The relative standard deviations for the substoichiometric extraction of MeAs(V) and Me₂As(V) are 0.55% and 1.1%, respectively. This substoichiometric speciation of methylated arsenic together with an earlier substoichiometric method for speciation of inorganic arsenic species was applied to the speciation of arsenic in an acid-digested solution of a macro-algae sample. It was demonstrated that almost all the arsenic in this solution was Me₂As(V) even after the digestion with nitric acid.     

Application of Tri-n-octylamine for the substoichiometric separation of chromium(VI) in activation analysis

A method has been developed for the substoichiometric separation of Cr(VI) by extraction with tri-n-octylamine solution in benzene from 0.1M H₂SO₄ solution. The method has been applied to the determination of chromium in silicon and aluminium by the neutron activation method.     

Sulfonephthalein dyes: Part VII. Chromogenic Reactions of Semi-Glycicethymol Blue

The chromogenic reactions of semi-glycinethymol blue have been studied spectrophotometrically and by complementary tristimulus colorimetry. The separation of the dye from a commercial product of glycinethymol blue is described. The five dissociation constants were determined; the means of the pK_a (H_iI) values for i= 5, 4, 3, etc. are —1.5, 0.3, 1.5, 7.5, and 12.7, respectively. Colour reactions with some metal ions are reported; the reaction with copper(II) is suggested for the determination of the composition of commercial samples of glycinethymol blue.     

Alkylidentriphenylphosphoran-komplexe von kupfer(I)- und silber(I)-chlorid : II. 1/1-komplexe

Stable 1/1 complexes have been obtained from the ylides methylene, ethylidene and isobutylidene triphenylphosphorane with CuCl, and from (C₆H₅)₃-P=CH₂ and AgCl. In these organometallic compounds of copper and silver the ylides are attached to the metal through the carbanionic donor atom. A cubane-type structure is proposed for the oligomers of the general formula [(C₆H₅)₃-PCHR·MCl]_n, (M = Cu, Ag; R = H, CH₃, CH(CH₃)     

Rapid radiochemical separation in neutron activation analysis : Part 1. The use of C18-bonded silica gel and selective complexation for determinations of manganese,copper and zinc in biological materials

A rapid radiochemical separation method based on the removal of metal ions by columns of C₁₈-bonded silica gel after selective complexation by 8-quinolinol, ammonium pyrolidinedithiocarbamate or cupferron is described for the determination of manganese, copper and zinc in neutron-activated biological materials. The removal of the metal ions, either by adsorption or by a combination of filtration and adsorption on columns of C₁₈-bonded silica gel, was investigated to optimise the separation procedure. Analysis of several National Bureau of Standards and International Atomic Energy Agency biological reference materials demonstrated the effectiveness of this technique. The method is simple and reliable and readily adaptable in all radiochemical laboratories. Furthermore, columns of C₁₈-bonded silica gel have been successfully recycled a number of times without deterioration.     

Comparative substoichiometric extraction of silver with potassium salts of ethyl,propyl, butyl,pentyl and benzyl xanthates

A rapid and sensitive substoichiometric radiochemical method has been developed for the comparative extraction and quantification of silver with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates from hydrochloric, nitric and sulfuric acid media into chloroform. The effect of 0.1–4M H⁺ ion concentration of the respective acid on the substoichiometric extraction of silver was critically studied. The efficiency of the method developed was tested by the determination of 10–100 μg silver in standard solutions with an average percentage of error better than 2. The methods developed have been utilized to determine silver content in photofilm washing collected from various photostudios in Tirupati, India.     

Production of metal atoms,clusters and complexes in pulsed discharge-excited jets : Studies via mass-resolved laser multiphoton ionization

A pulsed, high-voltage, discharge-excited nozzle source has been developed and exploited to study the possibility of sputtering and entraining various metal atoms into the gas expansion from the discharge electrodes. By appropriate choice of electrode materials, atomic beams of copper, silver, tin and lead have been generated and spectroscopically characterized by 2 + 1 laser multiphoton ionization with mass analysis. Sufficiently high atomic densities are achieved with this nozzle system that metal clustering also takes place, producing dimers such as Ag₂, species of mixed composition such as AgSn and trimers, Ag₃. In addition, chemical reactions have been observed which can be initiated in the discharge and which lead to the formation of metal–ligand complexes when suitable molecules are seeded into the carrier gas. Mass spectral evidence for two such silver complexes is presented.     

Solvent extraction of Mn/II/ with 2-propionyl, 1-naphthol oxime/2-PRONAPOX/ into chloroform

A rapid method has been described for the quantitative extraction of milligram amounts of Mn/II/ with 2-PRONAPOX into CHCl₃. The extraction coefficient /E/ of Mn/II/ between CHCl₃ and aqueous solution containing 0.2M NH₄Cl shows a maximum value of E=143 at pH 10.5. The percentage extraction is better than 98% in the pH range from 9 to 11 and an equilibration time of 6 min. The effects of anions and cations have been studied. The stoichiometry of metal: reagent determined by substoichiometric extraction and slope ratio method is found to be 12. The decontamination factors for most of the elements are better than 10⁴ in the substoichiometric extraction of Mn/II/.     

Study of the thermal behaviour of some transition metal acrylate-styrene copolymers

The processes of thermal destruction of copolymers of styrene with zinc, cobalt, nickel and copper acrylates have been studied by TG and the temperature characteristics have been determined. While the thermal stability of zinc-containing copolymers increases at higher metal contents, that of other metal-containing copolymers decreases and, depending on the metal, changes in the sequence Co > Ni > Cu. The kinetic parametersn, E _a ,Z and ΔS have been determined by the Horowitz-Metzger method and discussed. The resultingE _a sequence is in agreement with the observed sequence of thermal stability of the copolymers. The entropy factor suggests thermodynamic hindrance in the decomposition of copolymers of low thermal stability and a preference for the decomposition of copolymers of high thermal stability.     

Molecular orbital study of the selective hydrogenation of acetylene in aqueous metalcatalyzed tetrahydroborate systems

A computer program for geometry optimization based on a multivariate regression method is discussed. The configuration of the adsorbed species of acetylene on copper, silver and gold catalysts were obtained at the usual CNDO level. The adsorbed species of acetylene on copper and gold catalysts are M(ν² - C₂H₂) complexes, whereas that on silver is of vinyl form. The electronic-charge distribution, energy partitions and total Mulliken overlap population suggested that acetylene is effectively activated in these systems.     

Calculation of differential pulse polarographic curves for the reduction of complexes

A simple simulation is presented which allows calculation of differential pulse polarographic (DPP) curves for reversibly reduced complexes, applicable to all concentrations of ligand and to mixtures of up to four complexes. The simulation is employed to investigate the expected forms of DPP curves as a function of the values of overall formation constant (β_p) and ligand concentration.For a single 1:2 complex a splitting of the DPP curve is predicted at substoichiometric ligand concentrations for log β₂ values > ca. 10. These systems exhibit one peak at E° for the metal and a second broadened peak at a more negative potential.At stoichiometric ligand concentrations broad peaks are predicted which shift in potential with β_p in a predictable manner above a characteristic value of β_p.Assumed mixtures of two complexes at ligand concentrations substoichiometric with respect to the higher complex exhibit one or two peaks, with potentials and shapes dependent on the two β_p values.A method is proposed for the determination of the first formation constant in mixtures of two complexes, based on measurement of differences in peak potentials.     

Paper chromatography in the separation of ions : Separation of silver,copper and arsenic group elements

A paper Chromatographic study ot the separability of ions of elements of the silver, copper and arsenic groups, using different solvents and a number of complexing agents, reveals that the solvents consisting of (1) acetone, hydrochloric or acetic acid (with or without ammonium iodide) and (2) tert. -butyl alcohol, hydrochloric or acetic acid, promote the complete separation of at ; least five elements present in microgram amounts in a mixture. Other complexing agents, such as thiourea, bismuthiol I, bismuthiol II and 2-mercaptobenzothiazole are not very useful in the separation of the ions. The R_I., R_T values and the sequences of separation are tabulated to show their behaviour.     

Competitive transport of seven metal cations through bulk liquid membrane using 5,12-di(phenoxymethyl)-1,4-dioxa-7, 10-dithiacyclododecane-2,3-dione as carrier

The competitive metal ion transport of copper(II), cobalt(II), zinc(II), cadmium(II), silver(I), chromium(III) and lead(II) with a S-O donor compound was examined. Competitive transport experiments involving the metal cations from an aqueous source phase through an organic membrane into an aqueous receiving phase have been carried out using 5,12-di(phenoxymethyl)-1,4-dioxa-7,10-dithiacyclododecane-2,3-dione as the ionophore present in the organic phase. Fluxes and selectivities for competitive metal cations transport across bulk liquid membranes have been determined in a variety of chlorinated hydrocarbon and aromatic hydrocarbon solvents. The membrane solvents include: dichloromethane (DCM), chloroform (CHCl₃), 1,2-dichloroethane (1,2-DCE), and nitrobenzene (NB) and also in chloroform-dichloromethane (CHCl₃-DCM) and chloroform-nitrobenzene (CHCl₃-NB) binary mixtures. Although the selectivity for silver(I) cation in all of these organic solvents is fundamentally similar, but the most transport rate for Ag(I) was obtained in dichloromethane. The sequence of transport rate for silver ion in organic solvents was: DCM > CHCl₃ > 1,2-DCE > NB. A linear relationship was observed between the transport rate of silver ion and the composition of CHCl₃-DCM, but a non-linear behavior was observed in the case of CHCl₃-NB binary solution. The influence of the stearic, palmetic and oleic acids as surfactant in the membrane phase on the transport of the metal cations was also investigated.     

Fluorescence spectroscopy of laser vaporized species

The plasma produced by a Nd-Yag laser above a metal surface is measured by time resolved optical spectroscopy. The emission of atoms, ions and diatomics is observed for silver, copper and molybdenum. (Cu₂, ωe=263.3 cm^?1 X-state, 189.8 cm^?1 A-state). From these small species clusters are formed with a size distribution between 10 and 80 Å diameter measured by electron microscopy.     

Application of platinum gauze activated by hydrogen to the adsorption separation of silver traces and their determination by aas or spectrophotometry

A method ("electrosorption") has been developed for separation of silver from copper by its deposition through internal electrolysis with hydrogen adsorbed on a platinum surface. The silver can then be stripped and determined by atomic-absorption spectrometry or the dithizone method. The activation of the platinum surface with adsorbed hydrogen can be achieved either electrolytically or by passing hydrogen gas through the solution in which the platinum is immersed. The method of electrosorption has been successfully applied to determination of trace levels of silver in copper metal.