Complexometric Analysis Research Articles

Disulfo-NOPON—A new chelator for complexometric analysis and liquid-liquid extraction of stable isotopes and radionuclides of metal ions

The synthesis, chemical structure and physico-chimical properties of a new heterocyclic ligand, disulfo-NOPON (2,6-bis(5-(5-sulfonaphthalen-1-yl)oxazol-2-yl)pyridine), as well as its complexation ability, spectral and inter-phase partition properties of its complexes with metal ions, are described. Given potential applications of disulfo-NOPON in the liquid-liquid extraction and complexometric determination of ecotoxic and radioactive contaminants, studies were conducted on complex formation with stable and radioactive isotopes of Sr2+, Y3+, Ce4+, and UO22+ ions. Theoretical studies on complexes' structures have revealed that the formation of three isomeric complexes is possible, depending on the ligand's conformation. Furthermore, it has been found that under ``green'' extraction conditions, disulfo-NOPON forms different isomers of complexes in the organic and aqueous phases. Specifically, in the organic phase, disulfo-NOPON binds to a metal ion through the nitrogen atoms of its oxazole fragments, while in the aqueous phase, complex formation involves the participation of the oxygen atoms within the oxazole moieties. The results indicate a strong correlation between theoretical results and experimental values of spectral parameters, stability constants, and inter-phase distribution coefficients of complexes. Based on this preliminary analysis, it is evident that disulfo-NOPON holds promise for the spectrophotometric and spectrofluorimetric analysis of uranyl ions in both aqueous and organic media. Additionally, it can be employed for the extraction-based accumulation of cerium ions, facilitating their subsequent quantitative analysis.

The complexometric analysis of the copper and nickel content in co-presence in the coordination complexes with nitrilo-tris(methylenephosphonic acid)

The complexometric analysis of the copper and nickel content in co-presence in the coordination complexes with nitrilo-tris(methylenephosphonic acid)

Crystallization kinetics of calcium carbonate at a stoichiometric ratio of components

The formal kinetics of calcium carbonate crystallization in aqueous solutions is studied at a stoichiometric ratio of Ca2+ and CO32- ions. The kinetics of the process was monitored by convenient and reliable methods (complexometric analysis for calcium in an aqueous solution and energy dispersive and microscopic measurement of solid particle sizes). The effect the temperature and degree of supersaturation have on the periods of induction and mass crystallization and the equilibrium concentration of calcium ions in solution is estimated at continuously controlled pH and solution ionic strength. The kinetic parameters (n, k, τ1/2, Ea) of calcium carbonate crystallization are calculated. It is shown that calcium carbonate with a calcite structure formed at a stoichiometric ratio of reagents, and changes in the temperature (25–45°C) and the solution’s degree of supersaturation (2–6) within the considered range had no effect on the characteristics of the solid phase.

Synthesis, properties of lanthanide trifluoroacetate complexes with 2-azacyclononanone and X-ray crystal structure of [Sm(CF 3COO) 3(AZA) 2·(H 2O)] 2·2AZA

Lanthanide trifluoroacetate complexes (Ln=La, Pr, Nd, Sm, Tb, Gd, Tb, Er) with 2-azacyclononanone (AZA) were synthesized and characterized. Complexometric analysis with EDTA and microanalytical procedures agree with the general formula Ln(TFA) 3 ·3AZA; thermogravimetric curves in N 2 dynamic atmosphere show their thermal stability until about 100 °C. The europium emission spectrum indicates more than one Eu 3+ symmetry centre. The X-ray structure of the samarium complex consists of dimeric species where the metal atoms are connected through four TFA bridges, a monodentate TFA, two O-bonded AZA ligands and a water molecule complete the coordination sphere about each samarium.

Thermal behaviour of tin(II) complex with 8-hydroxyquinolinate in the solid state

Tin(II) complexes with 8-hydroxyquinolinate in solid state have been obtained by adding aqueous ammonium to a solution containing stannous chloride and 8-hydroxiquinoline in medium of HCl and acetone up to pH 5 and 9, respectively. The products obtained show the same composition, Sn(C9H6ON)2; however there are some differences regarding both the thermal behaviour in an oxidant atmosphere and morphology. These products were characterised by elemental and complexometric analysis, TG and DTA curves, infrared and X-ray diffractometry. TG curves show, above 448 K, the partial oxidation on air atmosphere of Sn(II) complexes to Sn(IV) complexes, SnO(C9H6ON)2. This behaviour does not depend only on pH in which the compounds were obtained but also on the heating rate in TG curves. Sn(II) complexes volatilise almost completely on nitrogen atmosphere and partially on air atmosphere depending on the oxidation degree of the compound.

Complexometric analysis using an artificial intelligence driven robotic system

Systeme permettant de determiner les conditions optimales du titrage complexometrique des cations metalliques, d'automatiser l'analyse et d'effectuer la detection du virage par spectrometrie d'absorption

Analytical methods for RE-Co alloys

Total RE, Co and Fe in mischmetal and its cobalt alloys are determined by visual complexometric methods and instrumental x-ray fluorescence techniques. As Fe causes interference in the determinations of RE and Co and its own determination is affected by the presence of Co, it is removed by precipitation. The iron is determined from the precipitate and RE and Co from the filtrate. Accuracy of the method is checked by analysing synthetic mixtures of RE, Co and Fe. The individual REs in mischmetal are determined by x-ray fluorescence method. The analysis technique is based on comparison of the oxides of the test samples with standards (both in pressed pellet form) in the appropriate composition range. The total RE content of mischmetal determined through complexometric analysis is compared with the total RE determined through x-ray fluorescence.

Complexometric analysis of magnetic materials by means of automatic titrations

An analytical method based on automatic potentiometric titrations was developed for the analysis of magnetic material (e.g., Ba2Zn2Fe12O22). The elements were separated by extracting iron(III) as its chloride in diisopropyl ether and by precipitating barium as its sulphate in the presence of disodium dihydrogen ethylenediaminetetraacetate (EDTA). After separation, the iron and zinc were complexed with EDTA, buffered at pH 5 with ammonium acetate solution and back-titrated with standard iron(III) chloride solution by using platinum-wire and saturated calomel electrodes. Barium sulphate was dissolved in EDTA and ammonia solution, buffered at pH 10·1 and back-titrated with standard zinc nitrate solution at mercury|mercury-EDTA and saturated calomel electrodes. A complete analysis of the magnetic material was performed on as little as 10 mg of sample. A Tacussel Titrimat automatic titrator was used for all of the determinations. Results accurate to within 0·35 per cent. were obtained. A similar procedure can also be used to analyse different magnetic samples.

Complexometric analysis of multicomponent systems

Abstract

Redox-complexometric determination of iron and cobalt and its application to the analysis of multi-component alloys

A redox-complexometric determination of iron and cobalt is based on potentiometric titration of iron with EDTA, followed by that of cobalt with iron(III) chloride after addition of 1,10-phenanthroline. This method simplifies the complexometric analysis of more complicated materials.

Rapid complexometric analysis of brass with CTDA

A method for the analysis of brass is presented. The lead, iron, nickel and zinc components are determined titrimetrically with the complexing agent CDTA (disodium dihydrogen 1,2-diaminocyclohexane N,N,N',N'-tetraacetate [also known as HexaVer]). The copper and the tin are weighed as metallic copper and as stannic oxide. The method is more rapid and convenient, especially for routine analysis, than the all-gravimetric procedure and it provides at least equal accuracy and precision.

Calculations in Complexometric Analysis

Complexation in Analytical Chemistry A Guide for the Critical Selection of Analytical Methods Based on Complexation Reactions. By Anders Ringbom. (Chemical Analysis: a series of Monographs on Analytical Chemistry and Its Applications, Vol. 16.) Pp. x + 395. (New York and London: Interscience Publishers, a Division of John Wiley and Sons, 1963.) 113s.

The complexometric analysis of pyro- and triphosphates—I: Stability constants of the proton and metal complexes of the acids

The stability constants of the proton and some metal complexes formed by pyro- and triphosphoric acids at 25° have been evaluated from potentiometric titration measurements.

Triethylenetetramine- N, N, N', N'', N''', N'''-hexa-acetic acid as a new titrimetric reagent

The disodium salt of triethylenetetramine- N, N, N', N'', N''', N'''-hexa-acetic acid (TTHA) has been used for complexometric determination of a great number of metals and the existence of bimetallic complexes of most bivalent elements has been proved. Tervalent elements form bimetallic complexes too, except for bismuth, thallium, indium and lanthanum. By using EDTA and TTHA it is possible to determine some binary mixtures of elements without screening reagents. The new types of displacement reactions : Me 2X + 2Y ⇄ 2MeY + X MeX + Y ⇄ MeY + X (X and Y are the anions of TTHA and EDTA) can be used for complexometric analysis. These possibilities are briefly discussed.

Application of atomic absorption spectroscopy to the determination of calcium in saliva.

THE importance of salivary calcium concentration of the environment in the solubility of tooth and enamel is readily apparent. As with other biological fluids, numerous methods, ranging from classical oxalate–permanganate titration and emission flame photometry to the more recent complexometric and colorimetric techniques, have been used to estimate the calcium content of saliva. Unfortunately most of these methods have certain disadvantages. The oxalate–permanganate method requires relatively large amounts of saliva, time-consuming centrifugation, washing and titration within a narrow temperature-range. Its accuracy has been questioned because of incomplete precipitation of the oxalate or loss of some calcium oxalate during the washing process1. Another devious procedure involves a complexometric analysis of calcium and magnesium in saliva followed by a separate colorimetric determination of magnesium, calcium being obtained as the difference2. Several complexon-titration techniques using erio-chrome black T, murexide or plasmo corinth indicators were tested on saliva. They were found unsatisfactory because the colour shift at the end-point was either too gradual and indistinct or, in the case of murexide, the colour faded too rapidly.

Indirect Complexometric Analysis with Aid of Liquid Amalgams

Indirect Complexometric Analysis with Aid of Liquid Amalgams