A solid phase radioimmunoassay for triiodothyronine using antibody-immobilized serum albumin microspheres

A solid phase radioimmunoassay for triiodothyronine (T₃) has been developed using antibody-immobilized serum albumin microspheres. Antibody albumin microspheres were prepared using a spinning disc aerosol generator. The low density of the antibody-albumin microspheres gives greater mobility for the particles there by ensuring better kinetics to the antigen-antibody reaction. The assay has a single incubation of one hour at 37° C and the separation of the antigen-antibody complex is accomplished by centrifugation. The sensitivity of this assay is 0.3 ng/cm³ and has a range of 0.3–4 ng/cm³.     

On the reliability of equilibrium data of the charge-transfer complex between 2,3-dichloro-1,4-naphthoquinone and hexamethylbenzene

In view ofHammond's warning⁶ about the Conspiracy of errors, found in the case of low values of equilibrium constants of charge-transfer complexes a case is made out for redetermining the values for the system hexamethylbenzene—2,3-dichloro-1,4-naphthoquinone. Uncertainties in the parameters were estimated using theLiptay ⁸ matrix procedure. The solvent used was dichloromethane. The following data were obtained at 25°C: vC T = 22,220 cm^–1;E _A=0.99 eV;K =2599±57 l²·cm^–1·mol^–2. _max= 1020 ± 148 cm^–1··1;K=2.55±0.37 l·mol^–1; –H=2.7±0.3 kcal·mol^–1.With 1 Figure     

Synthesis,Spectral Properties,and Crystal Structure of {Methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl) hydrazonato(2-)]oxovanadium(V)}

The hydrazino complex {methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl)hydrazonato(2-)]oxovanadium(V)}, VO(p-NO₂bhbzac)OCH₃, (1), has been prepared by the direct reaction of bis(benzoylacetonato) oxovanadium(IV), VO(bza)₂, with p-NO₂-C₆H₄C(O)NHNH₂, p-NO₂bh, in CH₃OH. The resulting compound contains benzoylacetone-(p-NO₂)benzoyl hydrazone as tridentate Schiff base-type ligand and OCH₃ group as Lewis base, both ligated to vanadium. The crystals are orthorhombic, with Z = 8, space group Pbca, a = 11.699(5) Å, b = 14.035(5) Å, c = 22.564(5) Å, R1 = 0.0756 and wR2 = 0.1302. The crystal structure demonstrated the square-pyramidal geometry of the VO_oxo(ONO)O coordination sphere with the oxo ligand at the apical position. The electronic absorption spectra revealed a ligand-to-metal charge-transfer (LMCT) band in the near UV region at _max = 23,700 cm^–1 (B = 5640 dm³ mol^–1 cm^–1) in CH₃CN, _max = 23,420 cm^–1 (B = 5550 dm³ mol^–1 cm^–1) in DMSO, and _max near 26,950 (sh) cm^–1 (B = 10,550 dm³ mol^–1 cm^–1) in CH₂Cl₂. The FT-IR spectra of (1) show the characteristic strong (V = O) stretching vibration at 993 cm^–1 and support the view that the oxovanadium complex is pentacoordinated and monomeric.     

Molybdenum phosphate glasses modified by Cu2O

Glasses in the system Cu₂O-P₂O₅-MoO₃ were prepared. The transformation temperature of glasses,T _g, ranges from 122 to 436°C and depends strongly on their composition.T _g values are mainly controlled by the oxygen-packing density. The structure of glasses was studied by infrared spectroscopy. The presence of various phosphate and molybdate units, from discrete monomeric to those with three-dimensional networks, has been observed. The electrical conductivity of prepared glasses depends mainly on Cu₂O content and varies from 10^–14–1cm^–1, for the glass free of Cu₂O, to 10^–6–1cm^–1, for glasses with compositions near of the binary Cu₂O-MoO₃ composition.This work was supported by grant No 1/731/94 of the Slovak Grant Agency for Science. The paper was presented on TERMANAL'94, XIII. International Conference on Thermal Analysis, October 1994, High Tatras, Slovakia.     

Coordination chemistry of alkali and alkaline earth cations: Synthesis and crystal structure of potassium(benzo-15-crown-5)2 [3,5-dinitrobenzoate(3,5-dinitrobenzoic acid)2]

The interaction of K(35-Dnb) (35-Dnb=3,5-dinitrobenzoate) with benzo-15-crown-5 (B15C5) in ethanol yields a charge-separated sandwich structured complex [K(B15C5)₂]⁺[35-Dnb(35-DnbH)₂]^– even when equimolar amounts of reactants were used and no external 35-DnbH was added to the reaction mixture. The complex (KC₄₉H₅₁O₂₈N₆, FW=1211.1), is monoclinic,P2₁/c,a=11.063(2),b=10.680(1),c=46.548(8) Å, =91.629(2)⁰,Z=4,D ₀=1.485 g/cm³,D _c=1.468 g/cm³, CuK =1.5418 Å, =17.01 cm^–1, 2<130⁰,F(000)=2520,T=298 K. FinalR for the 6618 observed reflections was 0.071. In the sandwich moiety, the K⁺ is 10-coordinated through all the oxygens of the crown molecules (K⁺–O, 2.76–3.11 Å). The 35-Dnb anion lies 5.3 Å below the lower crown mean plane and is charge separated with respect to K⁺ (K⁺–O^–>7 Å) but undergoes strong hydrogen bonding (2.59 and 2.49 Å) through each carboxylate oxygen with the carboxylic protons of two separate 35-DnbH molecules. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82014 (52 pages).     

Mechanism of the oxidation of L-ascorbic acid by the bis(pyridine-2,6-dicarboxylate)cobaltate(III) ion in aqueous solution

A detailed investigation of the oxidation of L-ascorbic acid (H₂A) by the title complex has been carried out using conventional spectrophotometry at 510 nm, over the ranges: 0.010 [ascorbate] _T 0.045 mol dm^–3, 3.62 pH 5.34, and 12.0 30.0 °C, 0.50 I 1.00 mol dm^–3, and at ionic strength 0.60 mol dm^–3 (NaClO₄). The main reaction products are the bis(pyridine-2,6-dicarboxylate)cobaltate(II) ion and l-dehydroascorbic acid. The reaction rate is dependent on pH and the total ascorbate concentration in a complex manner, i.e., k _obs = (k ₁ K ₁)[ascorbate] _T /(K ₁ + [H⁺]). The second order rate constant, k ₁ [rate constant for the reaction of the cobalt(III) complex and HA^–] at 25.0 °C is 2.31 ± 0.13 mol^–1 dm³ s^–1. H = 30 ± 4 kJ mol^–1 and S = –138 ± 13 J mol^–1 K^–1. K ₁, the dissociation constant for H₂A, was determined as 1.58 × 10^–4 mol dm^–3 at an ionic strength of 0.60 mol dm^–3, while the self exchange rate constant, k ₁₁ for the title complex, was determined as 1.28 × 10^–5 dm³ mol^–1 s^–1. An outer-sphere electron transfer mechanism has been proposed.     

Solid phase radioimmunoassay of triiodothyronine (T3) using antibody coupled carboxymethylcellulose powder

The paper describes a solid-phase radioimmunoassay for triiodothyronine (T₃) using antibody coupled to carboxymethylcellulose powder. The free carboxylic acid groups of cellulose are covalently coupled to the amino groups of the antibody using 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride. Immobilized antibody thus prepared was used in a solid-phase radioimmunoassay of T₃. The assay has a sensitivity of 0.18 g/l, and a range of 0.18–4 g/l. Satisfactory correlation was obtained when this assay was compared with a T₃ assay based on dextran coated charcoal separation system (Y=0.95X+0.15 g/L; r=0.98).     

Molecular Structure of Neodymium Tribromide from Gas-Phase Electron Diffraction Data

The structural investigation of molecules in the vapor over neodymium tribromide was performed by synchronous gas-phase electron diffraction and mass spectrometric (GED/MS) experiments at 1110(10) K. Besides the monomeric molecules (NdBr₃), a small amount (0.7%) of the dimer (Nd₂Br₆) was detected. For NdBr₃, the thermal-average bond length r _g (Nd–Br) of 2.675(6) Å was determined. The equilibrium structure was estimated to be planar (or nearly planar) with r _e (Nd–Br) of 2.659(7) Å. Three vibrational frequencies were estimated using the GED data: ₁ = 193 cm^–1, ₂ = 35 cm^–1, ₄ = 41 cm^–1. The structural parameters of Nd₂Br₆ could not be refined and were constrained at the estimated values during the analysis.     

Apparent molal heat capacities and volumes of pyridine and methyl-substituted pyridines in aqueous solution at 25°C

We have made calorimetric measurements leading to apparent molal heat capacities of pyridine and four methyl-substituted pyridines in aqueous solution at 25.0°C. Measurements of densities of the same solutions have led to apparent molal volumes. The results are as follows: pyridine, _C ^° = 305.7 J–°K^–1-mole^–1 and _V ^° = 77.5 cm³-mole^–1; 2-methylpyridine, _C ^° = 370.0 J–°K^–1-mole^–1 and _V ^° = 94.3 cm³-mole^–1; 3-methylpyridine, _C ^° = 380.2 J–°K^–1-mole^–1 and _V ^° = 93.7 cm³-mole^–1; 4-methylpyridine, _C ^° = 378.9 J–°K^–1-mole^–1 and _V ^° = 94.3 cm³-mole^–1; 2,6-dimethylpyridine, _C ^° = 441.8 J–°K^–1-mole^–1 and _V ^° = 109.9 cm³-mole^–1. These _C ^° and _V ^° values are discussed in terms of effects of substitution of CH₃-for H– in the various solute molecules.The research reported here was carried out in the Department of Chemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4.     

Ferromagnetic long range ordering in copper(II) maleate monohydrate

Summary The magnetic properties of copper(II) maleate monohydrate, Cu(C₄H₂O₄)·H₂O, have been measured in the 1.8–66 K range. Magnetic susceptibility and isothermal magnetization measurements on powdered samples reveal a transition to a ferromagnetic state in this layered compound. The transition to the ordered state occurs at T_c=4.0 K. The positive value of 8.0 K for the Weiss constant in the paramagnetic region confirms the ferromagnetic nature of the interactions. The magnetic susceptibility data above 3T_c may be fitted with a Heisenberg quadratic layer expression with the best-fit parameters J=+4.3 cm^–1, g=2.0, and zJ=+0.42 cm^–1. The e.p.r. spectrum at room temperature indicates orthorhombic symmetry. A complex containing the isomeric form of the ligand, copper(II) fumarate dihydrate, has also been prepared and its magnetic properties determined in the 80–300 K range. The data may be accomodated by two-dimensional theory with J=+1.05 cm^–1, g=2.09, and zJ=+0.10 cm^–1.     

Electronic and ESR spectroscopic study of thiocyanate-containing coordination compounds of titanium(III) in alcohol solutions

In an investigation of electronic and ESR spectra, it has been established that titanium(III) with the thiocyanate ion (in ethanol) forms distorted tetrahedral and octahedral complexes. The tetrahedral compounds, which are hydroxo complexes of titanium(III) that contain one hydroxyl group and three thiocyanate ions in the coordination sphere, give signals in the ESR spectra with g_o=1.960, A_o=15.0·10^–4 cm^–1 g=1.958, A ^Ti =26.4·10^–4cm^–1, g= 1.691, A^Ti=9.0·10^–4 cm^–1. In the ESR spectra of liquid solutions, additional splitting on the nitrogen atoms is manifested(A _o ^N =2.2·10^–4 cm^–1), which indicates bonding of thiocyanate ions through the nitrogen atom. The pseudo-octahedral complexes of titanium(III), containing from two to six thiocyanate ions in the coordination sphere, are characterized by d-d absorption bands in the 520–590 nm region; and at 77°K, they give anisotropic ESR signals. On the basis of the temperature dependences of the equilibrium constants for the reaction of conversion of the tetrahedral complexes to the octahedral complexes, and also the lifetimes of the tetrahedral complexes, values have been estimated for the heat of reaction (H=26.8 kJ/mole) and the entropy change (S=–1.66 kJ/mole·°K) of the equilibrium process, and also the activation energy for the reaction of titanium(III) thiocyanate formation (E=37 kJ/mole).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 560–567, September–October, 1985.     

Extraction and micro-determination of vanadium(V) in the environment with α-phenylstyrylacrylo-substituted hydroxamic acid and Aliquat 336 and inductively coupled plasma atomic emission spectrometry

A selective and sensitive method for the microgram determination of vanadium(V) with -phenylstyrylacrylohydroxamic acid by selective extraction of the blueish violet vanadium-hydroxamate complex with Aliquat 336 from acidic medium is described. The effect of thiocyanate on the extraction is discussed. The vanadium-hydroxamate complex has _max 553 nm and molar absorptivity 7.8 × 10³ l mol^–1 cm^–1, while the mixed 121 complex, vanadium-hydroxamate-Aliquat 336, has _max 546 nm and molar absorptivity 8.2 × 10³ l mol^–1 cm^–1. The system obeys Beer's law in the range 0.3–10.0 mg l^–1 vanadium. Sandell's sensitivity is 0.00624 g cm². The sensitivity is increased twentyfold by inductively coupled plasma atomic emission measurements on the extract and the detection limit is more than 1 ng ml^–1. Vanadium is determined in standard alloys, rock, environmental and clinical samples.     

Low temperature absorption spectra of KMnO4 in KClo4

The permanganate spectrum has been remeasured at liquid hydrogen and helium temperatures using spectrographs with reasonably high dispersion. Evidence is found for four absorption band systems. The first one is assigned as ¹ A ₁ ¹ T ₂ and displays a great deal of vibrational structure starting with the 0–0 line located at 18,072 cm^–1. The second transition found at 25,000 to 30,000 cm^–1 is rather featureless. The third transition with maximum at 33,000 cm^–1 shows a simple progression in quanta of 750 cm^–1. The fourth band is completely featureless with maximum intensity at 43,500 cm^–1. These findings are compared with a simplified SCF LCAO MO calculation.

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Zusammenfassung Das Permanganat-Spektrum wurde bei Temperaturen von flüssigem Wasserstoff und Helium unter Verwendung eines ausreichend auflösenden Spektrographen neu vermessen, wobei vier Absorptionssysteme gefunden wurden. Dem ersten von ihnen wurde ein ¹ A ₁ ¹ T ₂-Übergang zugeordnet; es besitzt eine ausgeprägte Vibrationsstruktur (0–0-Bande bei 18,072 cm^–1, während das folgende zwischen 25,000 und 30,000 cm^–1 kaum eine Struktur zeigt. Der dritte Übergang mit Maximum bei 33,000 cm^–1 zeigt einfache Progressionen entsprechend Quanten von 750 cm^–1. Die vierte Bande schließlich ist vollkommen strukturlos und hat ihr Maximum bei 43,500 cm^–1. Diesen Daten wurden die Ergebnisse einer einfachen SCF-LCAO-MO-Rechnung gegenübergestellt.

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Résumé Le spectre du permanganate de potassium a été réétudié aux températures de l'hydrogène et de l'hélium liquide en utilisant des spectrographes à dispersion raissonnablement élevée. On trouve la preuve de la présence de quatre systèmes de bandes d'absorption. Le premier, attribué à ¹ A ₁ ¹ T ₂, possède une forte structure vibrationnelle commencant à la bande 0–0 située à 18.072 cm^–1. La seconde transition située entre 25.000 et 30.000 cm^–1 est plutot sans structure. La troisième transition avec un maximum à 33.000 cm^–1 présente une progression simple de 750 cm^–1. La quatrième bande est complètement sans structure et a son maximum vers 43.500 cm^–1. Ces observations sont comparées avec un calcul simplifié SCF LCAO MO.

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NATO Postdoctoral Fellow 1965–66.     

Mass,size and shape of micelles formed in aqueous solutions of ethoxylated nonyl-phenols

The study was extended to analysis of mass, size and conformation of micelles formed in aqueous solutions of ethoxylated nonyl phenols. The results obtained by ultracentrifugal technique between 293 and 323 K have proved that the slightly ethoxylated nonyl phenols form micelles with high molecular mass and larger size at constant temperature, while the increasing length of the ethylene oxide chain favours formation of micelles of smaller molecular mass and size. The transformation of conformation from oblate to spherical shapes ensues with increasing temperature at constant ethoxy number or with ethoxylation at constant temperature. The second virial coefficient decreases with increasing temperature and decreasing ethoxy number. In accordance with the earlier conclucions, the change of the second virial coefficient relates to enhanced variation of monomer solubility, stabilization of micelle structure and increased deviation from ideal behaviour of a given micellar system.Symbols a major axis of micelle, Å - a _m attractivity factor, cm³ erg molecule² - b minor axis of micelle, Å - c concentration, g dm^–3 - c _b equilibrium concentration at the bottom of the cell, g dm^–3 - c _m equilibrium concentration at the meniscus of the cell, g dm^–3 - c _o initial concentration in the cell, g dm^–3 - c _M critical micellization concentration, mol dm^–3 - e eccentricity - f _IS Isihara-constant - f/f _o frictional ratio of micelle - amount of water in micelle per ethoxy group, mol H₂O/mol EO - n aggregation number, monomer micelle^–1 - n _EO number of ethoxy groups - r distance of Schlieren peak from the axis, cm - r _b distance of cell bottom from the axis, cm - r _m distance of cell meniscus from the axis, cm - R _h equivalent hydrodynamic radius of micelle, Å - s _t sedimentation coefficient, s - reduced sedimentation coefficient, s - reduced limiting sedimentation coefficient, s - ¯v _t volume of micelle, cm³ micelle^–1 - partial specific volume of solute, cm³g^–1 - partial specific volume of solute reduced to 293 K, cm³ g^–1 - B _a, B_e constants, cm³ mol g^–2 - B ₂ second virial coefficient, cm³ mol g^–2 - M _m ^a mass average apparent molecular mass of micelle, g mol^–1 - M _m mass average molecular mass of micelle corrected withB ₂, g mol^–1 - M _m ^cM mass average molecular mass of micelle belonging toc _M, g mol^–1 - M ¹ mass average molecular mass of monomer, gmol^–1 - N _A the Avogadro's number, molecule mol^–1 - R universal gas constant, erg mol^–1 K^–1 - T temperature, K - _t ^o dynamic viscosity of solvent atT temperature, g cm^–1 s^–1 - dynamic viscosity of solvent at 293 K, g cm^–1 s^–1 - _t density of solution atT temperature, g cm^–3 - _t ^o density of solvent atT temperature, g cm^–3 - density of solvent at 293 K, g cm^–3 - angular velocity, rad s^–1 - time, s     

Zum Spingleichgewicht5T2−1A1 in Fe(II)py 2 phen(NCS) 2

Zusammenfassung Die magnetischen, spektralen und strukturellen Eigenschaften des gemischten Amminkomplexes [Fe(II)py ₂ phen(NCS)₂] werden diskutiert. Der Orbitalparamter liegt mit 11 700 cm^–1 nahe der Spinpaarungsenergie für den mittleren kovalenten Fall 11 000 bis 12 000 cm^–1 und erlaubt so ein Spingleichgewicht zwischen den Spektralzuständen⁵T₂–¹A₁. Dieses Gleichgewicht wird durch magnetische Messungen bei verschiedenen Temperaturen nachgewiesen.

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On the spin equilibrium⁵T₂–¹A₁ in [Fe(II)py₂phen(NCS)₂]

The magnetic, spectral and structural properties of the mixed ammine [Fe(II)py ₂ phen(NCS)₂] are discussed. The orbital parameter of about 11 700 cm^–1 near to the spin-pairing energy for the mean covalent case 11 000 to 12 000 cm^–1 allows a spin equilibrium between the spectral states⁵T₂–¹A₁, put in evidence by the magnetic measurements at different temperatures.

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Mit 3 Abbildungen

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Herrn Prof. Dr.H. Nowotny gewidmet.     

Volumetric Properties of Aqueous 2-Chloroethanol Solutions and Volumes of Transfer of Some Amino Acids and Peptides from Water to Aqueous 2-Chloroethanol Solutions

Densities and apparent molar volumes of aqueous 2-chloroethanol were determined at temperatures from 15.0 to 34.4°C using digital densimetry. The results of the volumetric measurements have been used to calculate the following thermodynamic quantites at 25°C: V ₂ ^o = 55.05 ± 0.02 cm³-mol^–1, (V ₂ ^o/T)_p = 0.01486 ± 0.00318 cm³-K^–1-mol^–1, and (² V ₂ ^o/T ²)_p = 0.02972 ± 0.00318 cm³-K^–2-mol^–1. Partial molar volumes of transfer from water to 1 mol-dm^–3 2-chloroethanol have also been determined for L-glycine, L-alanine, L-serine, L-glutamic acid, and L-aspartic acid at 35.0°C. The transfer results have been explained in terms of the nature of the interactions of the groups in the solute and solvent. Hydration numbers of L-glycine and L-alanine have also been calculated in aqueous 2-chloroethanol.     

Sorption of Cu2+ ions by chitin and chitosan from aqueous solutions. Molecular structure of complexes formed

The sorption of Cu²⁺ ions by chitin and chitosan from aqueous solutions has been investigated, as well as the molecular structure of the complexes formed. The static exchange capacities have been determined, equal to 3.5 and 0.25 mmole/g for chitosan and chitin, respectively, and the partition coefficients (5000 and 70 g/ml). It has been shown that in complex formation a bond with the amino group is formed as the result of the substitution of a proton in the latter. The EPR spectra of these complexes have been obtained and their radiospectroscopic parameters determined (g = 2.334,g = 2.054,A = 0.0156 cm^–1, andB = 0.0028 cm^–1 for chitin, andg = 2.231,g = 2.048,A = 0.0192 cm^–1, andB = 0.0025 cm^–1 for chitosan). For chitosan the ligands are two nitrogen atoms of the amino groups and two oxygen atoms of the hydroxyl groups in the position C³ of adjacent glucosamine rings; for chitin, the oxygen atoms of the acetyl groups take part in addition in the complex formation. The analysis of the radiospectroscopic parameters and their comparison with published data lead to the conclusion that the Cu²⁺ complex with chitosan has a tetragonal symmetry, while the complex with chitin most probably has an octahedral structure.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2305–2311, October, 1992.     

Spectrophotometric determination of molybdenum(V) by extraction of its 2-(2′-furyl)-3-hydroxychromone complex

A simple method is described for the rapid spectrophotometric determination of molybedenum in synthetic and industrial samples containing 0.1-5% Mo. Molybdenum is reduced with ascorbic acid at room temperature in 1 mol dm^–3 H₂SO₄ and extracted with chloroform after adding 2-(2-furyl)-3-hydroxychromone (FHC). The yellow colour of the 1 2 Mo-FHC complex is measured at 414 nm against a reagent blank. Beer's law is obeyed over the range 0-2.7 g Mo cm^–3 of solvent phase. The molar absorptivity and Sandell's sensitivity are 5.18 × 10⁴ dm³ mol^–1 cm^–1 and 0.0018 g Mo cm^–2, respectively. Relative standard deviations are 0.2% for solutions and 0.5–1.5% for solid samples. Interference from tungsten and tin is removed by adding citrate and EDTA, respectively, while niobium and tantalum are masked by fluoride. Many elements such as V, Fe, Ti, U, Mn, Cr, Co, Ni, Re, Ru, Pt, Rh, Se, Au, Bi, Zr, Th, Ce, As and Al do not interfere even in large amounts, but antimony always interferes. Among the anions and complexing agents, only thiocyanate interferes seriously.     

Study of SO2 adsorption on titanium dioxide by IR spectroscopy and thermal desorption

Conclusions At least two different forms of chemisorbed SO₂ have been identified on the surface of anatase. The weakly bound SO₂ (a low-temperature peak with T_max=405–445 K, H_ads =85.7 kJ/ mole) is characterized by IR bands at 1330 and 1141 cm^– and is stabilized on coordinatively-unsaturated titanium ions. The strongly bound SO₂ (high-temperature peak with T_max=550–615 K) has a band at 1070 cm^–1. The thermal stability of SO₂ chemisorbed on TiO₂ is lower than on -Al₂O₃.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 503–505, March, 1989.     

Thiazolylblue tetrazolium bromide — a new spectrophotometric reagent for determination of manganese

A method has been developed for the micro-determination of Mn(VII) by the selective extraction of the MnO₄ ^– anion with thiazolylblue tetrazolium bromide from acidic medium. The molar absorptivity of the complex is 1 × 10⁴lmol^–1cm^–1 at 250 nm and the system obeys Beer's law in the range 0.1–1.75 gml^–1 Mn(VII). The composition and stability of the complex are discussed. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: extraction constantK _ex = 3.16 × 10⁴, distribution constantK _D = 21.85 and association constant =1.45 × 10³. Manganese(VII) was determined in soils and plants. The determination was carried out without preliminary separation of manganese.