Simultaneous differential kinetic determination of cobalt and nickel based on on-line complex formation and ligand substitution reaction using a stopped-flow FIA system

A differential kinetic method utilizing a stopped-flow FIA system is proposed for the simultaneous determination of cobalt and nickel at sub-ppm levels in mixtures. The method is based on the large difference in the rates of the ligand substitution reaction of the metal complexes of 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline (PSAA) with nitrilotriacetic acid. The apparent reaction rate for the Ni-PSAA complex is more than 100 times larger than that for Co-PSAA complex. The relative standard deviations in the analysis of binary mixture of 0.50 g/ml cobalt and 0.30 g/ml nickel were 1.9% and 2.1%, respectively (n=7). The sample throughput is about 20 h^–1. The effect of various ions was also studied. The proposed method has satisfactorily been applied to synthetic samples containing different ratios of cobalt and nickel 1/12 to 10/1.     

Simultaneous kinetic determination of copper, cobalt and nickel by means of -group interchange reactions

The kinetic determination of copper, cobalt and nickel in binary and ternary mixtures without prior separation is described. The methods are based on the difference in the reaction rate of interchange of - groups between thiosemicarbazide and 6-methylpicolinaldehyde azine in the presence of these ions at pH 4.5. Through these reactions the corresponding metal thiosemicarbazone complexes are formed. Various ratios of these ions at the 10(-5)M level can be determined photometrically by either the logarithmic extrapolation method or a combined initial-rate and fixed-time method proposed here for the first time.     

Simultaneous kinetic determination of metal ion mixtures based on a ligand substitution reaction

The rates of the ligand substitution reactions between 2-(4-sulfophenylazo)-l,8-dihydroxy-3, 6-naphthalenedisulfonic acid (SPADNS) complexes of Co²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ and EDTA (or CDTA) have been studied at 25.0°C, pH 8.0–9.3, by stopped-flow spectrophotometry. The reactions are first order in SPADNS complex and in incoming ligand. The absorbance change during the reaction progress can be kinetically separated for each component of a mixture, so that metal ions down to 10^-6 M can be determined. Components of very high reactivity, such as Cd²⁺, Mn²⁺ or Zn²⁺, can also be determined as part of a multicomponent mixture.     

Chemical analysis of mixtures of some heavy metals by means of differential reaction rates of ligand substitution reactions

The simultaneous determination of some heavy metals in their mixtures is described. The method is based on the differential reaction rate of ligand substitution reactions involving ethyleneglycol bis(2-aminoethylether)N,N,N',N'-tetraacetic acid (EGTA) and 4-(2-pyridylazo)-resorcinol (PAR). Various combinations at the 10^-6M level of heavy metal ions such as manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) can be determined photometrically.     

Formation of cobalt, nickel and copper complexes with murexide in ethanol-water mixtures

The complexation reactions between murexide and Co²⁺, Ni²⁺ and Cu²⁺ in C₂H₅OH-H₂O mixtures have been investigated spectrophotometrically. The formation constants of the 1:1 complexes formed increase in the order Co²⁺ < Ni²⁺ < Cu²⁺ for all solvent mixtures studied, and log K_f is a linear function of the mole fraction of ethanol. The heat of complexation was determined calorimetrically for the nickel and copper complexes. The values of ΔH° and ΔS° are solvent-dependent, and all three complexes have negative ΔH° and positive ΔS° values.     

Amperometric determination of copper, cadmium and nickel and their binary mixtures with methyldithiobiuret

Summary Copper, cadmium and nickel have been estimated amperometrically in ammoniacal ammonium tartrate and potassium nitrate (pH 8.0–9.5) using methyldithiobiuret as the titrant. The advantage of the oxidation potential of the reagent have been put to a practical use in these determinations. Furthermore, by the combined use of the cathodic current of a reducible ion (Cu²⁺) and the anodic current of the reagent simultaneous determination of the two components of binary mixtures (e.g., copper-cadmium and copper-nickel) in a single operation has also been achieved. The process is rapid and yields reproducible results within the limits of experimental errors.

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Amperometrische Bestimmung von Kupfer, Cadmium und Nickel sowie ihren binären Gemischen mit Hilfe von Methyldithiobiuret

Zusammenfassung Die Bestimmung wird in ammoniakalischer Ammoniumtartrat- und Kaliumnitratlösung (pH 8,0–9,5) durchgeführt. Dabei wird das Oxydationspotential des Reagenses ausgenutzt. Durch Messung des kathodischen Stromes des reduzierbaren Ions (Cu²⁺) und des anodischen Stromes des Reagenses konnten die Bestandteile binärer Mischungen (z.B. Cu/Cd, Cu/Ni) gleichzeitig bestimmt werden. Das Verfahren ist schnell und liefert gut reproduzierbare Ergebnisse.

     

Divalent nickel,cobalt and copper complexes of a tetradentate N6 macrocyclic ligand

Summary Divalent nickel, cobalt and copper salts react with 2,6-diaminopyridine and acetylacetone to form complexes containing a 16-membered N₆ tetradentate macrocyclic ligand. The complexes are characterised as distorted octahedra of the M(TML)X₂ type where M=nickel(II), cobalt(II) and copper(II); TML=tetradentate macrocyclic ligand and X=Cl, Br, NO₃ or NCS. The ligand coordinates through all the four azomethine nitrogen atoms which are bridged by acetylacetone moieties. Pyridine nitrogen does not participate in coordination, a fact supported by far i.r. studies. The magnetic, electronic and i.r. spectral studies indicate that the complexes have lower symmetries and the amounts of distortion calculated in terms of DT/DQ applying normalised spherical harmonic Hamiltonian theory indicate that these complexes are moderately distored.     

Analysis of some binary and ternary oxide mixtures by inelastic neutron scattering

Aluminium, iron and silicon have been determined in a number of binary and ternary oxide mixtures at levels>1% by measuring the gamma-lines emitted as a result of inelastic neutron scattering.     

Fluorimetric determination of ammonia, hydrazine and hydroxylamine and their mixtures by differential kinetic methods

Summary A differential rate principle is described by the determination of binary mixtures involving synergistic effects and tested by determining mixtures of ammonia, hydrazine and hydroxylamine. The reagent 2-hydroxybenzaldehyde azine has been found to react with these amines via interchange reactions of =N-groups. The reactions were fluorimetrically monitored by using a common product, 2-hydroxybenzaldehyde hydrazone ( _ex=355 nm, _em=465 nm). Mixtures of these amines can be determined in different ratios with a r.s.d. of ±1.5%.

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Fluorimetrische Bestimmung von Ammoniak, Hydrazin und Hydroxylamin im Gemisch mit Hilfe von differentialkinetischen Verfahren

Zusammenfassung Das differentialkinetische Prinzip wird an Hand der Analyse binärer Gemische mit synergistischen Effekten beschrieben und auf die Bestimmung von Ammoniak, Hydrazin und Hydroxylamin angewendet. Das Reagens 2-Hydroxybenzaldehydazin reagiert mit diesen Aminen über Austauschreaktionen der =N-Gruppen. Die Reaktionen wurden fluorimetrisch über das 2-Hydroxy-benzaldehydhydrazon ( _ex=355 nm, _em=465 nm) ausgewertet. Mischungen können in verschiedenen Verhältnissen mit einer Standardabweichung von 1,5% analysiert werden.

     

Recognition and quantification of binary and ternary mixtures of isomeric peptides by the kinetic method: metal ion and ligand effects on the dissociation of metal-bound complexes

The kinetic method is applied to differentiate and quantify mixtures of isomeric tripeptides based on the competitive dissociations of divalent metal ion-bound clusters in an ion trap mass spectrometer. This methodology is extended further to determine compositions of ternary mixtures of the isomers Gly-Gly-Ala (GGA), Ala-Gly-Gly (AGG), and Gly-Ala-Gly (GAG). This procedure also allows to perform chiral quantification of a ternary mixture of optical isomers. The divalent metal ion Ca(II) is particularly appropriate for isomeric distinction and quantification of the isobaric tripeptides Gly-Gly-Leu/Gly-Gly-Ile (GGL/GGI). Among the first-row transition metal ions, Cu(II) yields remarkably effective isomeric differentiation for both the isobaric tripeptides, GGI/GGL using GAG as the reference ligand, and the positional isomers GAG/GGA using GGI as the reference ligand. This is probably due to agostic bonding: alpha-agostic bonding occurs between Cu(II) and GAG and beta-agostic bonding between Cu(II) and GGI, each produces large but different steric effects on the stability of the Cu(II)-bound dimeric clusters. These data form the basis for possible future quantitative analyses of mixtures of larger peptides such as are generated, for example, in combinatorial synthesis of peptides and peptide mimics.     

Simultaneous determination of cobalt(III)-copper(II) and cobalt(III)-nickel(II) mixtures by differential kinetic methods

A procedure is reported for the simultaneous determination of binary mixtures of cobalt(III)-copper(II) and cobalt(III)-nickel(II) by differential kinetic methods based on complex formation reactions with 3-(1H-1,2,4-triazolyl-3-azo)-2,6-diaminotoluene. The single-point method is used in both cases. The simultaneous determination of Co-Cu and Co-Ni is possible in the concentration range from 10/1 to 1/1. The interference caused by various ions is also studied. The method has been used to determine cobalt-copper and cobalt-nickel mixtures in synthetic samples, hydrofining catalysts and low alloy steels.     

Determination of copper,cobalt and nickel by circular thin-layer chromatography

Summary A method for the microdetermination of copper, cobalt and nickel from a mixture containing 40 metal ions by circular thin-layer Chromatographic technique is described. The procedure is simple; the chromatoplate takes about 2 minutes for its development and other metal ions do not interfere with the determination. The recovery of copper, cobalt and nickel is better than 98%. The apparatus for the concentration of test solution before TLC analysis is also described.

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Zusammenfassung Die Mikrobestimmung von Kupfer, Kobalt und Nickel in Gemischen von 40 verschiedenen Metallionen im Wege der zirkulären Dünnschichtchromatographie wurde beschrieben. Die Vorgangsweise ist einfach; die Entwicklung der Chromatogramme erfordert 2 Minuten, fremde Metallionen stören nicht. Die Ausbeute an Kupfer, Kobalt und Nickel ist besser als 98%. Ein Gerät für das Einengen der Probelösung vor der DC-Analyse wurde gleichfalls beschrieben.

     

Molten potassium thiocyanate: The reactions of some compounds of iron,cobalt, nickel,copper and zinc

The electronic spectra of four transition metal cations stable in molten potassium thiocyanate [Fe(II), Co(II), Ni(II) and Cu(I)] are reported together with their reactions and those of three unstable cations [Fe(III), Co(III) and Cu(II)] with a variety of anions including cyanide, cyanate and sulphide. A novel reduction of zinc(II) sulphate is also reported.     

Drug-excipient compatibility studies in binary and ternary mixtures by physico-chemical techniques

This work is part of a systematic study undertaken to find and optimize a general method of detecting the drug-excipient interactions, with the aim of predicting rapidly and inexpensively the long term stability of a pharmaceutical product and speed up its marketing. Here, in particular, the compatibility of haloperidol with several excipients (PVP, magnesium stearate and α-lactose) in binary and ternary mixtures, both as prepared and ball-milled, has been assessed by thermal methods, electron microscopy, IR spectroscopy and X-ray diffraction. The differences between the experimental behaviour of the systems and that expected as weighted average of similarly treated pure components are interaction indicators. The DSC has proven to be, among the selected analytical techniques, the most sensitive and specific in assessing the compatibility. A strong interaction has been observed between PVP and haloperidol. It is favoured by the mechanical stress and is more evident in the composition 20:80. On the contrary, α-lactose and magnesium stearate were found to be compatible with the drug.     

Spectrophotometric determination of copper, nickel, cobalt, iron and manganese as their pyridine thiocyanates Simultaneous determination in mixtures

Spectrophotometric determinations of copper, nickel, cobalt, iron, and manganese, based on the chloroform extraction of the metal pyridine thiocyanates, have been investigated. Optimum conditions require the pH of the aqueous solution to be in the range about 5–8; tartaric acid is used to prevent precipitation of hydrous oxides. An excess of pyridine must be used because chloroform readily extracts pyridine from the aqueous solution. Results are improved by making the extraction from a solution of high ionic strength (2 or above), which is provided by magnesium nitrate. Perchlorate decreases the absorbance, but the effect is essentially constant over a perchlorate concentration range of 0.8 to 2M. Although the metal pyridine thiocyanates are extracted by benzene, substituted benzenes, and halogenated hydrocarbons, chloroform is superior to other solvents in extraction efficiency and in colour stability of the extracted species. An example is given of the simultaneous determination of copper, nickel, cobalt, and iron in the same solution. Anions that also form metal pyridine compounds must be absent.     

激光热透镜光谱分析法同时测定铜、钴和镍研究

基于2-(5-NO2-吡啶-2-偶氮)-1-羟基-8-氨基萘-3，6-二磺酸与铜(Ⅱ)、钴(Ⅱ)和镍(Ⅱ)反应酸度的差异及热透镜信号强度的加和性，建立了激光热透镜光谱法同时测定铜、钴和镍的新方法。测定铜、钴和镍的线性范围依次为0～200ng/mL、0～200ng/mL和0～100ng/mL，检出限依次为2ng/mL，2．5ng/mL和1ng/mL。方法已用于合成样品及人发样中铜、钴和镍的同时测定。     

Back titration with mercuric nitrate in alkaline medium; analysis of binary mixtures of barium, strontium or magnesium together with lead, cobalt, nickel or copper

Summary Mercuric nitrate has proved to be a suitable back titrant for EDTA solutions in excess of the amounts reacting quantitatively either with one of the tetrad lead, cobalt, nickel or copper in the presence of one of the triad barium, strontium or magnesium atPh 8 or 9, or with both cations atph 11. This behaviour was the basis underlying the analysis of binary mixtures of the possible combinations between cations of the two groups. The end-points were detected potentiometrically with reasonable jumps and with fair agreement with the theoretical equivalence points.     

Preparation and characterisation of copper,cobalt and nickel complexes of tetradentate N6 macrocyclic ligand

Macrocyclic complexes of copper, nickel and cobalt were synthesised via template reactions. These 14-membered N₆ tetradentate macrocyclic complexes were characterised by magnetic, conductance, electronic and IR spectral studies. The macrocyclic ligand coordinates through the four azomethine nitrogen atoms which are bridged by 2,3-butanedione, moieties, but far IR spectra suggest that the pyridine nitrogens are not coordinated. These macrocyclic complexes are considered to have distorted octahedral configurations.